Check online multiple times a day and if once you get to WDW you don't have online access, then call. We got to WDW on DD's 1st trip and realized there was no way she was going to be making pre-park opening ADRs with the time change. I cancelled our pre-park opening Tusker House the morning before we were eating there and was able to pick up a 9:30 instead, I'm sure someone was thrilled to get our pre-park ADR that day. Also, last December, I had been trying to get San Angel for a month for the last night of our trip after DD suddenly decided she wanted to eat there. I was checking online on my phone, and I got the ADR I wanted the night before we wanted to eat there! People cancel right up to the day! Good luck!!!