I hope this doesn't happen to you, but this just happened to me: The week after February break, so, theoretically a slow time, I had an 8:10 ADR for BoG. Park was supposed to open at 9. 3 weeks ago, they just changed the open time to 8AM, making my delicious breakfast as well as my potential touring advantage obsolete. Stinky, right? Just bear in mind to keep checking park hours. Coveted reservations made 180 days ahead can become cancelled ADRs 21 days ahead.