A system provides a notification associated with joining a communication session based on trigger events that occur at a time other than a scheduled start time for the communication session. For example, the notification informs a user who organizes the communication session of a predefined join event that occurs when another user joins the communication session. The predefined join event may occur at a time that is different than a scheduled start time (e.g., before the scheduled start time). Moreover, the notification can include an embedded control that, when activated by the organizing user, causes a device of the organizing user to transmit a join request to join the device to the communication session.