Make a Roblox integrated sessions board so that when someone claims a session, it appears on the board with the status of the session, who claimed it etc. then, when it gets close to the time of the session, a join button appears so you can join the training center directly from your main game. But make it so that there are 2 boards, one for training center, one for the main game. So one has the join button, the other does not.

An in-game board to show upcoming trainings and if they're claimed or not. Also the ability to join the training center through the board.