Patience, patience!
As goofyfordisney pointed out, last year the really good rates didn't come out until September. While they may not be quite as good this year, the late summer rates currently available give hope that the Nov-Dec rates will be within 5% of last year's bargains.
While you could make reservations now "just to be sure" and change them later when better rates become available, that's probably a waste of time. I am pretty sure that no resort sells out during Value Season (possibly excepting ASMo); that's why rates are so much lower then! So unless you have very specific requirements, there should be no harm in waiting. And it certainly makes no sense to make reservations at a rate you're not willing to pay.
If you're going during Thanksgiving or Christmas holidays, all bets are off. But even then we'll probably see better rates become available.