Let them know when you make your ADR they will note it...they will give you a # to call, call that a week in advance and then 48 hours in advance. Most full service restaurants can whip up something on the spot though. I have multiple food allergies and last trip made ADR's only 2-3 hours before I ate and was always able to find SOMETHING to eat! Plus EVERY WDW restaurant can make up a fruit plate for dessert!