I am reminded of Israel's sojourn in Egypt. God said that the time of their dwelling in Egypt would be 400 years.
Gen 15:13 And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years
Yet, they were in Egypt for 430 years.
Exo 12:40 Now the sojourning of the children of Israel, who dwelt in Egypt, was four hundred and thirty years.
What comes immediately to mind is, why the discrepancy. God had prepared and chosen Moses to be the man to lead the children of Israel out of Egypt. Moses knew this at least 40 years prior to the event (390 years in). At this time Moses was 40 years old. Yet, like many of us, Moses got ahead of God and tried to accomplish this work in his own time and own flesh. Moses was a capable and able leader. No doubt a military genius, for Luke tells us that he was learned in all the wisdom of the Egyptians and mighty in word and deed. But he got ahead of God and tried to pull off the exodus 10 years early.
Act 7:23-25
(23) And when he was full forty years old, it came into his heart to visit his brethren the children of Israel.
(24) And seeing one of them suffer wrong, he defended him, and avenged him that was oppressed, and smote the Egyptian:
(25) For he supposed his brethren would have understood how that God by his hand would deliver them: but they understood not.
The result was a 40 year trip to the back side of the desert while God finished preparing Moses. The cost...God's plan was delayed 30 years. The implication...Like Moses, our choices are important, and can impact what God has chosen to do.
Let me throw in another scripture. Paul speaks in Romans 11 of Israel's blindness. He says that this blindness will continue until the fullness of the Gentiles be come in. This is implying the full number of the Gentiles. So, it seems, the coming of the Lord is not linked to a fixed date in time, but rather to the completion of a fixed number of people. In Matthew 24:14, Jesus gives a very similar statement. He says that the gospel must be preached to the whole world, and then the end. It is these two scriptures and their implication that drives much of our present day Bible translation and missions programs. Many desire to hasten the coming of the Lord, so they do their best to reach the world with the Gospel.
So it seems clear that, in some cases, not only does God not contradict the will of man, but the will of man has the ability to effect the plans of God.
Notice that I said "effect" and not "change". There are events ordained that will come to pass no matter the actions of man, but, like Moses, man can effect the timing of these events.
However, we cannot say that God does not contradict man's will in all cases. For instance, it was not the will of Elymas to be blind for a season. In fact, I would surmise that this blindness was definitely against His will. Nor was it the will of Saul to be knocked off His horse and blinded. Yet it occurred. The list could continue.
So I think I could ask and answer a few questions this way...
Does God ever contradict the will of man? Yes.
Does man ever have the power to delay or altar God's plans? Yes.
I know that God has ordained that I do certain things in my lifetime. He has shown me one of them. I am, honestly, battling some fear of the unknown in stepping out in faith and obedience to do what He as told me to do, although I am determined to do it, no matter the fear, etc.. Yet I have known men with calls on their lives who have rejected those calls, or who have, for a period of time, put off obeying God. Through doing so these men have caused the will of God, ultimately, to nothing in their lives. What God willed for them was not done.
This question is one of what I might call the lifetime questions. The directions that we could go with it and the ensuing discussion could be endless. I personally think it is wise for a person to look carefully at all of the Biblical examples and simply take them at face value.
I will admit readily that I have a very limited understanding of God and His workings among man. I think we are all in that boat together. There is much that I do not know. The best I can do is look at scripture and say, "Well, it seems to have happened this way right here."
Blessings.