Have you checked out Tikiman's site? It's fantastic and has a conceirge phone number that you can call and have them make all your arrangement. From what I understand, the conceirge makes every effort to contact guests 2-3 weeks before they arrive to make all the arrangements. If you want something special and hard to get like Cindy's or Chef Mickey's, I would contact them ASAP.
Have a great B-day. I keep dropping hints to DH that a disney trip is what I want for my 40th.