I wouldn't necessarily cancel outright but just check a few times a day to try to modify to see if something else pops up. We were there on an 8am opening day and had a 10:20 breakfast reservation and it worked out perfectly- got a ton done and when the park was beginning to fill up we took a break and got some breakfast. 
(We snacked in the hotel room before hopping on the bus). I imagine something later will pop up eventually, we booked out trip 8 days out and no problem getting it with a little checking.
(We snacked in the hotel room before hopping on the bus). I imagine something later will pop up eventually, we booked out trip 8 days out and no problem getting it with a little checking.
