The Day of the Lord, in general, and the return of Jesus Christ for his own, in particular, are shrouded in mystery. Even Jesus, the Son of God, was willing to defer to his Father in the timing of these events (Matthew 24:36).
The decretive--or Sovereign--will of God assures us that God's plan for the ages will come about and that God will have the final word regarding the when and the how of its denouement. His permissive will, however, gives his volitional image-bearers a degree of latitude in shaping the when of that denouement, though not its how.
Since in the context of 2 Peter 3, Peter is exhorting believers to live holy and godly lives, by implication believers can fail to live up to God's standards for holy and godly living. Is God's decretive will in any way threatened by the spiritual lapses of his saints? No. The Day of the Lord and the return of Christ will proceed according to the Father's plan.
Who is to say, however, that that day is not affected by both our obedience and our disobedience? There are numerous instances in the Old Testament in which God's judgment on Israel for their disobedience was delayed because there were repentance and revival. In other words, God's timetable is affected in some way by our behavior, but exactly how and why it is affected is, again, shrouded in mystery, and mystery, of course, is the third general aspect of the will of God.
Peter gives us a little insight into that aspect of God's will when he says,
8 But do not forget this one thing, dear friends: With the Lord, a day is like a thousand years, and a thousand years are like a day. 9 The Lord is not slow in keeping his promise, as some understand slowness. Instead, he is patient with you, not wanting anyone to perish, but everyone to come to repentance.
Our conception and experience of time and its passing are in contrast to God's conception and experience of time. To us, a day is just a day and a thousand years is just a thousand years. To God, a day--as in "The Day of the Lord"--could be a thousand years and a thousand years as a day. As the creator and Lord of time, the Father is sovereign over time, and what takes man a thousand years to build can take God but a day.
By the same token, however, with man, a project or a job which could and should be accomplished in a day can drag on for a thousand years, due to delays, lack of funds, lack of vision, changes of mind, and a myriad of other factors. For an inexperienced handyman, a job he estimates to take a day could wind up taking several days. If the same man had God's perspective, he or she would be able to proceed according to schedule, knowing ahead of time what needs to be done, how it needs to be done, and the potential pitfalls that could delay its completion.
In like manner, God gives us some latitude, according to his permissive will. How much latitude? That will always remain a mystery.
Can God's children hasten or hurry up God's Sovereign will? Yes, they can. Is that hastening process affected in some way by our eagerly awaiting it? Yes, it is. The answer to the question of what hastening means is not and either/or answer but a both/and answer. To hasten is to wait eagerly, and to wait eagerly is to hasten. Exactly how these two parts of the answer are related will have to remain a mystery, I believe.