Hi, Jessica! Technically, you can book your "room only" vacation 499 days out, so that falls somewhere in early 2010. You can reserve a room, but the price will not be confirmed until the 2011 prices are posted, usually around August of each year.
I personally would wait until prices/packages are posted at the end of next summer to book. Until then, start browsing through the resort options at
www.disneyworld.com, and sign-up for e-newsletters from
www.allears.net and
www.mousesavers.com so you can be kept up to date on happenings in Walt Disney World and also stay informed on packages and special offers.
Plan out your dates, budget, and resort choices so you will be ready to plan your magical vacation!