Keep checking online everyday as often as you can. It's a credit card guarantee restaurant so people will cancel when their plans change.
As a group of 3, try that first, then try looking for 4 because the reservation system has a quirk that makes it harder for odd numbered groups to book a table. If you get a reservation for 4, just let the CMs at the podium know you are a group of 3. You will not be charged for the 4th person as long as at least 1 of you show up for the dinner. Also, everyone who will be at the table needs to be included so try for 3 or 4. Don't book a table for 2 thinking you can add a 3rd person at check in - because that person could be turned away.