Are you asking about the first flight of the day (or if 2 hours passed since the previous flight), or in general? Just curious.
Two people have now mentioned two hours since the previous flight. Is this an IAE limitation? It's a while since I flew aircraft with IAE engines, so it may well have slipped my mind. The magic number for CFM seems to be six hours: if the time elapsed since the previous flight is more than six hours, we can't do single engine taxi, and engines must be at idle for at least five minutes before applying take off thrust.