Of the four canonical gospels, most scholars believe that Mark was written first, followed by Matthew, then Luke, and finally a bit later by John. Papias, writing in the early second century and recalling what he claimed to be the words of John, called Mark “Peter’s interpreter,” meaning that he wrote according to Peter’s memory of the words and works of Jesus and not so much his own. So Mark’s gospel is really the gospel according to Peter.
Interestingly enough, Papias also stated that Mark’s record of Christ’s life was “not in proper order.” In other words, precise chronology was not his aim in writing. “For he had not heard the Lord nor had he been one of his followers, but, as [John] said, later became a follower of Peter, who adapted his teaching to the practical needs of the churches” (taken from The Early Christians in Their Own Words, compiled by Eberhard Arnold).
So there you have it. The first account of the life of Jesus, which was possibly written within twenty years of his death and resurrection, was never known to be 100% historically accurate. Not in its chronological sequence, at least. Bummer. So how are we to know what happened when? How are we to know for certain, for instance, whether Jesus cleansed the temple at the beginning or end of his ministry, or both?
The answer is simple: We can’t.
When it comes to the chronology of the gospels a precise harmony is out of the question. The best we can do is construct a general overview of Jesus’ ministry, noting when and where he spent most of his time, and from there go on to look at what all he was doing during each season of activity. For instance, we see that after his baptism Jesus spent a relatively brief span of time in and around Jerusalem, after which he withdrew again into Galilee (probably in conjunction with John’s arrest). And though it seems he was accustomed to return to the holy city each year for the feasts, he spent the majority of the next three years in the general area of his nativity.
For a more thorough consideration of this topic, check out Bill Heroman’s post on the chronology of the gospels. He can tell you a lot more than I can.