Recent redeye in F with my 25 month old who is plane obsessed. Was the early UA redeye from OGG to LAX.

FAs very friendly and asks son if he wants to meet pilot. Of course he says "YES" and we go up to cockpit and the very cool pilot shows him all the instruments and knobs and she even sets off a few alarms (TCAS) and he was in heaven. She kept going and going and even offered us a photo opportunity, which I declined for the timing reasons below.

The pilot was obviously going above and beyond the call of duty and probably didnt want to offend a F passenger. There is no way a 25 month old boy would ever leave a cockpit on his own accord. Is there an appropriate amount of time/activity in the cockpit after which you would pull your kids back to their seat?

I really got the sense that this UA captain would have delayed departure if my son wanted it -- obviously I was sensitive to that and pulled him after about 2-3 minutes of cockpit fun. Was that too long up there? Then again, if door is still open and the captain is game, should the parent just go with it until the pilot signals "time up"?