If you're trying to get it on the eighth day of your trip, don't be surprised if they tell you there's no availability the first day you call. Keep calling back each day, and eventually something should open.
It's a flaw in their system that we went through a couple of months ago when making CRT reservations. I called exactly 90 days out, and all of the "plus" days (days 2 through 7) of my trip had no availability. I kept calling back each day, and tables kept opening up, and we got exactly what we wanted. I don't know if they've fixed this or not since they went to the 180 day system, but my GUESS would be that the problem only got worse. The extra lead time probably disincentivizes them to watch inventory closely.