When you are viewing your reservations in List View, you can see how many tables are available.
On the top right corner of any Reservation Session tab is a breakdown of:
How many tables you have
How many seats these tables have (based on your Table Map)
How long until the next table will be available
The countdown is based on the Estimated Waiting Time set on the backend. As soon as a table is checked in, the estimated waiting time will count down.
Note: In the backend, you should set your Estimated Waiting Time to equal the Reservation Duration so you know how long it should be until a table is ready, based on how long a reservation goes for.
To see exactly which tables are available, and how long it will be until occupied tables are available, tap the seat icon and consult the popup.