I think the peer group thing is really important.
Not just now when your child is little, but later on as well. Or even more so.
My DS would go from being one of the oldest in his year to being one of the youngest. Potentially leave school at 17 (and then have to work until he is 102 the way things are going - what's the point in that??).
My SIL is head of a secondary school and she pointed out to me how hard it can be for somebody who happens to hit puberty late to also be the youngest in their class.
They won't be allowed to learn to drive with their peers, won't be allowed out as late as their friends, won't be able to participate in activities their peers might want to do (that might be a good thing, mind
).
I am not convinced that getting them through school young is necessarily doing them a service (any 12 year old Oxbridge genius has my full sympathy).
My village state primary school have been very good with DS, giving him extra work and encouraging him. He is currently in a composite class P3P4 and he has loved that. He also enjoyed circle time, PE, drama and arts with his P3 friends.
My meeting with the head is just to find out her thoughts what to do with him next school year when he is going to be in a 'straight' P4 having already done all the P4 work.
When I was about 12 or so there was vague talk about me being moved up a year which thankfully did not come to anything. I left school at 19 (not in Britain) with my peer group, I still did not have a clue what to do with myself. How on earth I would have coped if I had been forced to leave school much younger, I don't know
....