In most cardrooms, if there is no seat available for you when you arrive, you can put your name on a list to be seated when a seat opens up.
a Poker table seat-reservation list, provided in many card rooms, where latecomers may place their names to ensure themselves a seat when one opens up or otherwise becomes available.
A waiting list. A player would put his or her name on this list if there were no seats at the table at which they wish to play.
If there is no seat available for you when you arrive in a card room, you can put your name on a list to be seated when a seat opens up.