IIRC McCain was out of money and basically dead in the water after New Hampshire and Iowa. He really never got off the ground running until South Carolina, which means that he was effectively only beginning his campaign in February 2008. He pulled off a come from behind slaughter of the candidates who were left standing.
I frankly think that anyone who tosses their hat into the ring more than 6 months before the first primary is a fool.
Additionally if the Republican convention had been delayed by a month, McCain would be president today.
There are only two reasons why McCain was able to acquire the nomination. The first is that conservatives could not (or would not) rally and unite behind anyone. The second is the open primaries in several key states. McCain essentially backed into the nomination, winning it almost by default. He wasn't effectively beginning his campaign in February. He was resuscitating it.
McCain had been running for president since the late 1990's. He had everything in place except a real constituency in the Republican Party. His constituency, such as it was, was among independents, centrist Dems and lukewarm Reps. Conservatives were not going to support Romney. When Huckabee and everyone else dropped out, who was left?