Actions can be performed at a specified time out of the combat order. To do this, the specific action and the timing of when the action should be executed must be declared. The timing could be an opponent coming into view or a door opening. When the moment occurs, the current actor's turn is interrupted, and instead, the prepared action is executed. After that, the actor continues as usual or adjusts their plan to react to the new circumstances. If the timing did not occur until your next turn, the AP are lost and you continue as usual.