if you're booking your trip through disneyworld.com, log into your account (assuming you have already registered). Once you're logged in, go through pricing out your trip and choosing all your options. Once you get to the end, instead of choosing "book now", on the left side you'll see an option for "save for later". it does not guarantee that the reservation is yours (only a deposit will do that) but you can save all the details of your trip so when you're ready to put your deposit down, just log in and then go to the "My Disney Vacation" tab. click on "saved vacation offers". I belive it will hold your trip for a week.

I hope this helps !!!