We've actually had a lot of success with last minute reservations - when we're trying for only 1 or 2 nights. We've made reservations as late as "day of" on two different occasions.
We had the Thursday & Friday following the SS Member Cruise booked in a studio at OKW since last August. A few weeks ago - we decided to try and switch it to VWL. Friday was available, but not Thursday. So I went on the waitlist - and got the call yesterday - 2 weeks prior to check-in.
If you're flexible with your choice of resort - and even with studio vs 1BR - you might have better luck.
The only ones we've had problems with is getting the Sunday night prior to a federal holiday. "Those" you often need to book a little farther in advance. Last Memorial Day - we decided about 1-2 weeks ahead to try to go over - just for the night. We finally settled for a night at POR. Hated to blow all those points - but it was fun to try out the resort.
A co-worker of mine tried to get the Sunday prior to MLK day (just this past week) about 2-3 weeks in advance. No luck - she got a FW Cabin, instead.
It sure is nice to be close, isn't it?