Re: When did/would you let your child go to a sleepover? (non-family)
In the situation you presented, the answer would be a quick and flat-out no for us personally.
Our girls didn't sleep over with non-family until around age 10. Most of that had to do with their comfort level. Neither one of them would be allowed to sleep over with anyone with whom we are not good friends. My son is only 5 and he only sleeps over at his aunt's house, mostly because that's the only place he will go without us.