Get on line multiple times a day every day and check. I've been very sucessful getting unavailable places doing that. It might take me a few weeks (or a month), and one time I didn't get the place until we were at WDW and it was the night before we wanted to eat there, but I've almost always had something finally pop up. Before the ADRs went online, I never had any luck calling once a day and trying to pick them up. It is all a matter of timing and luck. If you don't get one before your trip, then go to the podium the minute CRT opens for lunch and ask if they can get you in at any time that day. Don't get your hopes up, but you might be surprised. I've occasionally seen people walk up and get in, although I've seen them be turned away more.