Old enough for them to have learned to socialize face to face.
I started on the computer in 1989.
When my kids were in about 6-7th grade (late 90s) I bought them 2 computer games.
My daughter didn’t like them and went back to books.
My son loved his chess program, got on his college chess team and ended up with a PhD in AI.
They didn’t get flip phones until high school.
Face to face is the way to go.