For the dessert party we had to pay the whole amount when making the reservation. Fortunately for us, we have most of the money for our June trip sitting in a savings account already so it didn't sting as much.
You only have to pre pay for the WOC Dessert Party. All of the other meals for parades and shows you do not. It says no refunds on the dessert party but I don't know if that is for sure or not.