There are two timers on the island the “Random” and “Fifteen”. The random timer is at the beginning of the game, it allows you the time to gather resources and to get your thoughts and plan together. The issue is, it is a random time! Also if some one decides to go full out crazy and activates a beacon then it throws you into the Fifteen!
The Fifteen-minute timer is the actually time for the game session. This is the amount of time allotted for you and all the other players to figure out where the evacuation point will be. So use your time wisely.