We've been there 3 times, and we've gotten pretty much what we wanted everytime. We have a big family, so we get a 2BR. Once, we booked at 11 months, but the other 2 times was around 8 months and 11 months out.
We're going next month, and got the 6 nights we wanted, booked right before the 7 month out time. Then, we ended up waitlisting for another Saturday night either before or after....
We ended up getting both! So, we've had pretty good luck, but we definitely are happy we bought there, to take advantage of the 11 month window.