You might. I went in early May last year, so not a super busy time, but it was tough to change reservations. We scheduled our ADR's a little early and ended up missing two of them because naptime (dd4) went too long. We tried to reschedule reservations at Boma and Ohana from 6:30ish to 8:30ish. We were told that there were no ADR's available for Boma all week, and Ohana didn't have an ADR open until 9:30. So, we ended up missing Boma and got ADR's for a TS lunch later in the week. That conversation went like this: do you have any ADR's at CP? WCC? Le Cellier? ANYWHERE? There were only three restaurants available out of all four parks and we ended up at LTT (which was suprisingly good). Soooo, you should be able to find someplace to eat if you change last minute, but it may not be your first choice.