Keep checking online because cancellations re-enter the reservation system almost immediately so it is a matter of being online checking when the cancellation appears.
With a party of 7 it gets harder because there are fewer large tables in the restaurants. You can also try for a party of 8 because the reservation system has a glitch that gives even numbers the edge. If you find a res for 8, as long as at least one person shows up for the reservation, you will not be charged for the missing person. Do not, however look for a reservation for fewer than your party - everyone needs to be included, even the youngest infant or non-eaters because of the fire code.
You can also split up your party and look for two reservations (e.g. 4 & 3) for the same time. When you check in you can request to be seated together, but there is no guarantee because you are booked for 2 smaller tables so this would work only if you are willing to be seated separately. As much as possible CMs will seat you together or near each other.
You can also subscribe to the cancellation thread for your month, but be sure to read the rules in the first post:
http://www.disboards.com/threads/new-cancel-thread-guidelines-may-november-links-here.1802381/
