Claiming and Blaming

Warning/Disclaimer: This post is about politics.
The following thoughts occurred to me this morning on the drive into work:
If Kerry wins the election in November, how long will he have to be in office before he starts taking credit for the way things are going with the economy?  Naturally, like any politician would, if it goes sour he will blame the previous President and the Republican party.  But what if it continues to recover and he takes office?  How much credit can he take for it, and when would it be an appropriate time to lay claim to having helped promote such a turn?
 
If Bush remains in office after the election, what will happen to all of the people who hate Bush to such an extent that they can't imagine living under his leadership for 4 more years?  Will these people wallow in the loss?  Will they actually put their passion to good use and begin working on the 2008 election with earnest?  If the economy continues to recover, will they accept the fact that it happened while Bush was in office?
 
It is my opinion that if the economy continues to improve, then it no longer becomes an issue in the election.  If it falters or recedes in any significant way, than I see it as becoming a very large issue.  Why?  Because people want as many reasons to hate and blame Bush as possible.  But if it turns as a positive thing for Bush, then it suddenly becomes a nonissue. Why?  Because people don't want to even consider that maybe something remotely positive has happened under his leadership.
 
I simply wonder how much time has to transpire between a change in leadership before people will begin to take credit, and how long afterwards can they continue to take the blame?