Get while the gettin is good-
As in leave wherever you are while your children are still acting normal or pleasant.
As in leave the location before they get too tired, hot, cold, hungry, bored or overstimulated.
A fine line to walk especially with moms that don't know you and/or whose children is acting like angels.
Often heard being muttered as in " Should have left while the gettin was good" by tired stressed out moms who have lost all pride as they drag their tear ridden screaming child to the car.