Hey,
Congratulations on your trip! The only suggestion I would make at this point is to try and determine whether you might want to stay on site at a Disney resort or rent a house or book an off site hotel. You should have a general idea about a year from your planned arrival date.
There are lots of pros and cons to both and the reason I suggest this is that if you have your heart set on a deluxe or moderate resort on Disney property, they tend to book well in advance.
For example, we love to stay at the Beach Club resort and we usually book a year in advance just to make sure we get the resort we want. The reservation fee is usually one nights stay and is fully refundable up a certain number of days in advance of your arrival (check this board or with Disney to find out what their cancellation policy is).
Also, if you do some investigation and determine what full service restaurants you want to eat at, you should book them as soon as you can (six months out). Sounds crazy but some places book up at this time. For example, one very popular place is to have lunch or dinner at Cinderella's Castle. If you want to get a reservation, I suggest booking it as soon as you can (six months prior to your arrival date).
Lastly, and most importantly, have lots of fun learning all about WDW. It helps make the time go faster!
This board is awesome for information but I also suggest mousesavers.com and allears.net.
Have fun!