I'm reminded of a statistic I read. 75% of the time you will spend with your child happens by age 12. I think I would eschew the phones until 13, purely because I'd never get that time back. Once they're adolecents and "too cool" to hang out with parents anymore, then fine, here's your phone, don't kill yourself.
Anyway, let's not assume everyone is a parent and ruin the whole online world with rules to "protect the children" made by the same people that never arrested any Epstein clients. We know they're not doing it to protect children. Let's not even pretend they are.