How well do kids have to be supervised?
For instance, at some age you can sleep in while your kid(s) are awake. How old do the kids have to be?
How old do your kids have to be for you to soak in the bath while they're awake?
How old do kids have to be for you to be really busy in another room while they're playing somewhere else?
How old do kids have to be for you to be mowing the lawn while your kids are alone inside?
How old before kids can play in the yard without you outside with them? How old before they can play in the neighborhood with other kids without a parent?
How old do kids have to be for you to go next door to chat with a neighbor while they're playing at home?