I know the answer to this one, only because I just asked it myself from my planner in hopes of trying to figure out the timeline (since I want to get my hair/makeup trial run done, and dinner with family).
Your rehearsal will be based on time availability by Disney--and it won't necessarily be the day before your ceremony (though you can try to book it). You need to go through your planner to book the rehearsal date/time, but you can only book it 30 days in advance of your wedding ceremony.
I think in the future, this and other planning question would go into the general forum, rather than trip reports/planning journals.
Hope this helps!
Tiffiny
