welcome to my world as my ds has peanut/tree nut allergies
when we were heading to wdw we were told the protocol is as follows:
-- inform the cm when making adr
-- call the restaurant directly 48 hours in advance (the booking cm will give you the #)
-- let the hostess know when checking in for your adr
-- inform the waiter/waitress when he/she greets you and ask to meet with a chef
-- walk the buffet line or review menu selections w/the chef
-- avoid all baked goods, even if you are told they are "safe" because they are NOT (ask me how i know!

) unless they are individually packaged (i.e. oreos from gift shop)
-- feel free to ask to have things individually prepared in the kitchen using clean utensils/pans to avoid any cross-contamination
-- remind waitstaff that desserts are mostly off limits, asking for ice cream or ice pop instead
we were blessed to have mostly great experiences and a little extra attention... ds got all the chefs to sign his autograph book as well as pose for a picture with him... many went out of their way to craft him a special dessert, and when they were unable to (i.e. garden grill) they made a big deal out of bringing him a good humor ice pop! he was thrilled and felt quite special!
good luck... feel free to ask specific questions!
also, p.s. are you flying? if so, what airline? some are now nut-free... others are not but have nut allergy plans in place... we've flown american and southwest and had great success w/both... we pre-boarded in both instances allowing time to wipe down all surfaces w/clorox wipes to insure no residue from previous passengers...