It depends on if you want to book the package or room only. Room only can be booked like 495 or 499 days out, I can't remember which. In one of the 2012 threads, someone said that sometime in August, the packages should be available to book for 2012. I'm not sure how far out you can book your flights, if you plan on flying.
We're planning on going in November 2012 (hopefully the finances will play nice so we can go). The plan is to be at WDW on our oldest DS's 15th bday.