I recommend early to mid october.
I go the last week of October, 1st week of November as my DD (and the rest of the state) has off from school so that is officially JERSEY WEEK!
Every where you go, you'll see one of us Jerseyians

I think we are the only ones down there besides a few others, LOL
Anyways, even though 1/2 the state of Jersey was there, the lines weren't bad and the weather was beautiful!
Only thing is, don't go too early in the month as Florida usually gets hit with the tail end of Hurricanes!
Disney got alot of rain, high winds last year into the beginning of October.