When is Too Old to go in the Restroom with Mom?

This may come as a surprise to some people, particularly the menfolk out there, but many things go on in the women's restroom which have nothing to do with actually going to the restroom.  There's the fixing of hair and makeup.  There's gossip (come on, like this is a surprise?), and there's a a lot of fixing of...things: nylons, bra, etc, etc.  In general once women are inside the restroom we kinda expect that if we flip our skirts up to fix something we won't be causing any trouble.  Then again...we could be wrong.

Recently I was in a restroom doing said fixing and had my skirt hitched up much higher than it would ever be in public when a boy somewhere around 7 or 8 years old wandered in with Mom right behind him.  His eyes got big and he stared (which was either because my legs were cute or because he could see just past mid thigh. maybe both) and his mother got all indignant and bustled him out of the room, while giving me death glare.

I'm pretty sure I wasn't doing anything that women don't do in front of the restroom mirror all the time. Kid and Mom are just lucky no one was rearranging their boobs, which folks do all the time.  So this brings me to my question.  At what age do you stop taking junior into your restroom and just stand outside the men's room while he does his thing and returns?  In my brain if they're old enough to head off to school they're plenty old to dart in, pee, wash hands and return.  If they're old enough that they're walking and talking on their own maybe bringing them in could be okay, but with a yelled warning...or find a store with a family rest room, which seem common enough.

Thoughts?

~J