Welcome!
It isn't too late!!! 4-15 is later than a lot of schools this year, I think, so it should make it easier.
If you are thinking of using a
travel agent (it can take a lot of the pressure off!) I'd recommend looking into
Dreams Unlimited. They only do Disney & will be so helpful you won't know how you could have planned the trip without them! Click on the Disney World reservations link in the top right corner of this page to get a quote. They will also look for discounts for you. Right now the the discounts for April are limited, but they will check periodically to see if they can get you a better deal.
I also like the unofficial guide, because it is cynical

Birnbaums is good for 1st timers, your library should have it. I like passporter because it has pockets for me to organize all of our travel documents & discount coupons & ticket stubs & well, you get the idea
Here are some other helpful links:
www.mousesavers.com
Deb's site
http://www.wdwig.com/
Passporter book & website
http://www.passporter.com/
All of the DIS discussion boards can be found here
http://64.225.125.24/forums/
It is so much fun planning! You'll have a great trip!
