I don't watch the clock, if they awaken after an hour and a half or three hours I let them sleep. It seems to depend on the day of the week how tired they are or how much activity we've had all morning.

However, the first one awake has to stay quiet and in their bed until all of the children are awake. If it's taking a really long time for the last one to wake up I'll start changing diapers or taking the others to the potty and getting snacktime ready. The child who sleeps the longest at my daycare right now is the 3 year old, he's the oldest and there have been times that all the others are finished snack and back in the toyroom/sleeproom to wake him.