I found this for you on the web.
BOOKING YOUR WALT DISNEY WORLD TRIP IN 2012 AND BEYOND
You can book rooms at Walt Disney World for 2012 up to 500 days in advance (which as I write this takes you into July 2012) right now. But there’s a couple of tricks and complexities.
You can’t do it on the Disney World website. You can only do it by calling Disney directly, or through a travel agent.
For dates beyond what are available on the Disney World website, you can only book rooms—not packages with tickets, the dining plan, and such. (You can add these to your reservation later.)
The prices you’ll be quoted will be 2011 prices. These will be wrong. The prices for the next year are usually announced in August of the prior year–so 2012 prices likely will come out in August 2011. This is also when the website is opened to 2012 reservations.
You will have to pay a deposit to hold your reservation. This deposit will increase when the final prices for 2012 come available, later this year.
When final prices come out, your travel agent will help you fix your deposits…and if any discounts come out, your travel agent can also help you take advantage of those! You can also add tickets and other parts of a package later, when final prices come out.
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Visit this link to find answers to some of CSR's FAQ.
Subject: When is the earliest you can book vacation? 
