A timer trigger fires when the given number of StopTime seconds has elapsed. The StartTime value is normally set to 0.0, so the timer starts when the mission is loaded. Setting the StopTime value to 5.0 (secs) will make actions are initiated by timer triggers when the stop time is reached - in 5 seconds from mission start.
StartTime - The time, in secs, when the timer is to start.
StopTime - The time, in sec, when the timer is to stop, & fire any actions linked.
OnScreenTimer - Set to True if an onscreen timer is to be rendered.
OneShot - Set to True means the action should only be fired once.
Actions - What actions to fire when the StopTime is reached.
Activated - The timer trigger is active, not waiting for any other event.
Notes: only one onscreen timer is possible (so if a new one is opened, it will replace any existing one).
Link a timer trigger and a dialog action by clicking on Property Set for the Actions property. This will bring up a list of items in the Elements box. Double click on an item in the Elements box to link the trigger and action. This will be shown both by a + sign appended to the name in the Elements box.