Now, the Kerry campaign had a plan. They were going to wait to a certain day in Fall '04 before launching the main campaign in order to tap into federal funding. So, generally a pretty good plan.
But let's say John decides to respond to the criticism quicker.
And, he avoids the mistake of over-responding and thereby legitimizing the criticism. Of course the Bush administration will themselves respond to a major change. As will the right-wing ideologues. In fact, John might go through eight years of his presidency as a steady middle-of-the-roader getting all kinds of things done, and still receiving all kinds of criticism from the right. This assumes of course that he's seen as responding competently to the '08 banking crisis and wins re-election.
And another interesting wrinkle is that a habit of abruptly changing plans likely doesn't serve someone well as Secretary of State, where a steady eddie approach probably gets more done in the long-term.