As Paul comes to the end of his letter, he wants to encourage and to challenge Timothy to his task. To do so, he reminds him of three things concerning Jesus.

(1) Jesus is the judge of the living and the dead. Someday, Timothy’s work will be tested, and that by none other than Jesus himself. Christians must do every task in such a way that they can offer it to Christ. They are not concerned with either the criticism or the verdict of others. The one thing they long for is the ‘Well done!’ of Jesus Christ. If we all did our work in that spirit, the difference would be incalculable. It would save us from being so touchy that we are offended by criticism; it would save us from the self-importance which is concerned with personal rights and personal prestige; it would save us from being self-centered and demanding thanks and praise for everything we do; it would even save us from being hurt by people’s ingratitude.

(2) Jesus is the returning conqueror. ‘I charge you’, says Paul, ‘by his appearing.’ The word is epiphaneia. Epiphaneia was used in two special ways. It was used for the clear intervention of some god, and it was especially used in connection with the Roman emperor. His accession to the throne was his epiphaneia, and in particular – and this is the background of Paul’s thought here – it was used of his visit to any province or town. Obviously, when the emperor was due to visit any place, everything was put in perfect order. The streets were swept and decorated, and all work was brought up to date so that the town might be fit for epiphaneia. So, Paul says to Timothy: ‘You know what happens when any town is expecting the epiphaneia of the emperor; you are expecting the epiphaneia of Jesus Christ. Do your work in such a way that all things will be ready whenever he appears.’ Christians should order their lives in such a way that at any moment they are ready for the coming of Christ.

(3) Jesus is king. Paul urges Timothy to action by the remembrance of the kingdom of Jesus Christ. The day comes when the kingdoms of the world will be the kingdom of the Lord; and so Paul says to Timothy: ‘So live and work that you will have an honorable place on the roll of its citizens when the kingdom comes.’

3. He must tell people of their faults: “Reprove them, rebuke them. Convince wicked people of the evil and danger of their wicked courses. Endeavour, by dealing plainly with them, to bring them to repentance. Rebuke them with gravity and authority, in Christ's name, that they may take thy displeasure against them as an indication of God's displeasure.”

Note: Interesting point. The rebuke of the minister is him attempting to show the displeasure God would have about the act or situation.

4. He must direct, encourage, and quicken those who began well. “Exhort them (persuade them to hold on, and endure to the end) and this with all long-suffering and doctrine.”

(1.) He must do it very patiently: With all long-suffering. “If thou do not see the effect of thy labours presently, yet do not therefore give up the cause; be not weary of speaking to them.” While God shows to them all long-suffering, let ministers exhort with all long-suffering.

(2.) He must do it rationally, not with passion, but with doctrine, that is, “In order to the reducing of them to good practices, instill into them good principles. Teach them the truth as it is in Jesus, reduce them to a firm belief of it, and this will be a means both to reclaim them from evil and to bring them to good.” Observe,

[1.] A minister's work has various parts: he is to preach the word, to reprove, rebuke, and exhort.

[2.] He is to be very diligent and careful; he must be instant in season and out of season; he must spare no pains nor labour, but must be urgent with them to take care of their souls and their eternal concerns.

Note: With the commentary from Ecclesiastes 11:6 we easily see that a minister must have a ministerial point-of-view in all things and by extension, the firstfruit must have a firstfruit point-of-view in all things all the time. This is another support to the idea of Assiduity.

5. He must watch in all things. “Seek an opportunity of doing them a kindness; let no fair occasion slip, through thy negligence. Watch to thy work; watch against the temptations of Satan, by which thou mayest be diverted from it; watch over the souls of those who are committed to thy charge.”

6. He must count upon afflictions, and endure them, make the best of them. Kakopathēson, endure patiently. “Be not discouraged by the difficulties thou meetest with, but bear them with an evenness of spirit. Inure [to accustom yourself to] thyself to hardships.”

7. He must remember his office, and discharge its duties: Do the work of an evangelist. The office of the evangelist was, as the apostles' deputies, to water the churches that they planted. They were not settled [over a specific place or church] pastors, but for some time resided in, and presided over, the churches that the apostles had planted, till they were settled under a standing ministry. This was Timothy's work.

8. He must fulfil his ministry: Make full proof of it. It was a great trust that was reposed in him, and therefore he must answer it, and perform all the parts of his office with diligence and care. Observe,

(1.) A minister must expect afflictions in the faithful discharge of his duty.

(2.) He must endure them patiently, like a Christian hero [a person full of courage and bravery].

(3.) These must not discourage him in his work, for he must do his work, and fulfil his ministry.

(4.) The best way to make full proof of our ministry is to fulfil it, to fill it up in all its parts with proper work. ~Matthew Henry Main

Now to the Matthew Henry Concise which covers verses 1-5:

People will turn away from the truth, they will grow weary of the plain gospel of Christ, they will be greedy of fables, and take pleasure in them. People do so when they will not endure that preaching which is searching, plain, and to the purpose. Those who love souls must be ever watchful, must venture and bear all the painful effects of their faithfulness, and take all opportunities of making known the pure gospel. ~Matthew Henry Concise

Now to the specific commentaries:

The verse is in seven parts, though the Barnes divides up one phrase into three parts for a total of nine. We will go with seven parts:

1] Preach the Word.
2] Be instant in season and out of season.
3] Reprove.
4] Rebuke.
5] Exhort.
6] With all longsuffering.
7] And doctrine.

1] Preach the Word.

Preach the word - The Word of God; the gospel. This was to be the main business of the life of Timothy, and Paul solemnly charges him in view of the certain coming of the Redeemer to judgment, to be faithful in the performance of it. ~Barnes Notes

2] Be instant in season and out of season.

Be instant - see the notes at Romans 12:12. The meaning here is, that he should be constant in this duty. Literally, “to stand by, or to stand fast by;” that is, he was to be pressing or urgent in the performance of this work. He was always to be at his post, and was to embrace every opportunity of making known the gospel. What Paul seems to have contemplated was not merely, that he should perform the duty at stated and regular times; but that he should press the matter as one who had the subject much at heart, and never lose an opportunity of making the gospel known. ~Barnes Notes

Quoted verse:
Romans 12:12
Rejoicing in hope; patient in tribulation; continuing instant in prayer.

In season - εὐκαίρως eukairōs. In good time; opportunely; compare Matthew 26:16; Luke 22:6; Mark 14:11. The sense is, when it could be conveniently done; when all things were favorable, and when there were no obstructions or hindrances. It may include the “stated and regular” seasons for public worship, but is not confined to them. ~Barnes Notes

Quoted verses...all speaking to seeking opportunity:
Matthew 26:16
And from that time he sought opportunity to betray him.

Luke 22:6
And he promised, and sought opportunity to betray him unto them in the absence of the multitude.

Mark 14:11
And when they heard it, they were glad, and promised to give him money. And he sought how he might conveniently betray him.

Out of season - ἀκαίρως akairōs. This word does not elsewhere occur in the New Testament. It is the opposite of the former, and means that a minister is to seek opportunities to preach the gospel even at such periods as might be inconvenient to himself, or when there might be hindrances and embarrassments, or when there was no stated appointment for preaching. He is not to confine himself to the appointed times of worship, or to preach only when it will be perfectly convenient for himself, but he is to have such an interest and earnestness in the work, that it will lead him to do it in the face of embarrassments and discouragements, and whenever he can find an opportunity. A man who is greatly intent on an object will seek every opportunity to promote it. He will not confine himself to stated times and places, but will present it everywhere, and at all times. A man, therefore, who merely confines himself to the stated seasons of preaching the gospel, or who merely preaches when it is convenient to himself, should not consider that he has come up to the requirement of the rule laid down by the apostle. He should preach in his private conversation, and in the intervals of his public labors, at the side of the sick bed, and wherever there is a prospect of doing good to any one. If his heart is full of love to the Saviour and to souls, he cannot help doing this. ~Barnes Notes

3] Reprove.

Or “convince;” See the notes at 2 Timothy 3:16. The meaning is that he was to use such arguments as would “convince” men of the truth of religion, and of their own need of it. ~Barnes Notes

Quoted verse:
2 Timothy 3:16 [See Lesson]
All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:

4] Rebuke.

Rebuke - In the New Testament the word is used to express a judgment of what is wrong or contrary to one’s will, and hence, to admonish or reprove. It implies our conviction that there is something evil, or some fault in him who is rebuked. The word in this verse rendered “reprove,” does not imply this, but merely that one may be in error, and needs to have arguments presented to convince him of the truth. That word also implies no superior authority in him who does it. He presents “reasons, or argues” the case, for the purpose of convincing. The word here rendered rebuke, implies authority or superiority, and means merely that we may say that a thing is wrong, and administer a rebuke for it, as if there were no doubt that it was wrong. The propriety of the rebuke rests on our authority for doing it, not on the arguments which we present. This is based on the presumption that men often Know that they are doing wrong, and need no arguments to convince them of it. The idea is, that the minister is not merely to reason about sin, and convince men that it is wrong, but he may solemnly admonish them not to do it, and warn them of the consequences. ~Barnes Notes

Note: One of my preaching points is that one person, even a minister [or any firstfruit], has no power, in and of himself, to convince anyone. You see this confirmed in this commentary. The argument of rebuke is to the Spirit of God in the person being rebuked. The true convincing will take place between God and that individual by and through the Spirit of God in them.

5] Exhort.

Exhort - See the notes at Romans 12:8.

6] With all longsuffering.

With all long-suffering - That is, with a patient and persevering spirit if you are opposed. ~Barnes Notes

With all longsuffering - or patience. The success of the Gospel ministry should be patiently waited for as husbandmen do for the fruits of the earth. Those that give into error, and oppose themselves to the truth, should be instructed in meekness; and those who are overtaken in a fault should be gently rebuked, and restored in such a spirit; and every exhortation should be pressed as persons are able to bear it: ~Barnes Notes

7] And doctrine.

And doctrine - The different modes of teaching suited to each. ~Adam Clarke

And doctrine - in a way that is instructive and teaching, and in agreement with the doctrine of the Scriptures, which are profitable for that purpose. ~John Gill

For the minister, he is to preach the Word of God, to look for any opportunity to use his ministerial gifts, to reprove, rebuke and exhort with all longsuffering and doctrine.  The members are to immerse themselves in the Word of God.  They are to look for every opportunity to invoke the power of the Holy Spirit and be an example of Christ.  They are to allow the Word of God, as well as the ministry to reprove, rebuke and exhort with all longsuffering and doctrine.  This is the lesson of verse 2.