By 7th grade, 10 feet is fine especially with a 28.5 ball.

CYO played a men's ball in 7th grade. And in my experience, coaching prevented kids from shooting 3s that shouldn't. I can think of only one kid growing up whose coach didn't keep him from chucking up 3s that he had no business taking. (That said, this past year, I've seen multiple games in second grade ball where coaches were not disciplining kids for chucking threes.)

When I transferred to public school in the 8th grade, I actually had to go back down to a 28.5 after being accustomed to a men's ball. That took some getting used to, and it likely was harmful not just sticking with the men's ball. I'd probably support using a men's ball in the 8th grade to have a year of experience prior to high school. I'd be fine continuing to use a 28.5 in the 7th grade for the main reason to permit players to start to be able to make decisions about outside shots.

However, I also played on 10 foot rims starting in 3rd grade because the gyms weren't equipped to change rim height.
I definitely support the lower hoops that made 2nd grade basketball possible. I'd be fine keeping them lower through fourth grade, but I'm pretty ambivalent.

I'd consider maybe through sixth grade, but I would guess that by that time, 10 feet would be fine. But it's been awhile since I've seen that level play much.