Methods and apparatus related to identifying an event task of a user, identifying one or more other attendees of the event, determining user arrival information for the user, and determining a notification to provide to at least one of the other attendees based on the user arrival information. The event task includes a starting time for an event and an event location, and the user arrival information is based on location information of the user and information associated with the event task. In some implementations, the user and/or the at least one of the other attendees may provide authorization for a notification to determined and/or sent. The notification may include information regarding the likelihood of the user arriving at the event before and/or after the starting time of the event.