When do DC's learn about perosnal space?

[NotaDisneyMum]

At what age to DC's become aware of their own and others personal space?

My DSS is eight and seems to have no clue about how his proximity makes other people feel, and when we have spoken to him about it, he shrugs and says it's OK because "he doesn't mind".

He's not push'y, and understands queueing etc - but if, for instance, someone is standing in front of something he wants to get at, he'll just squeeze in between, even if that means making firm physical contact with the person. It's not just at home with family, he'll do this to strangers in shops, public toilets, and I'm sure he does it at school as well - I'm thinking that it won't be long before he gets a thump, or accused of touching someone inappropriately - even though he really hasn't got a clue that what he is doing makes other people uncomfortable! In a lot of ways he is quite immature for his age - which seems to be more noticeable now as some of his school peers have become pre-teen in attitude/interests - but as he is mixing with them, I'm worried that this lack of understanding could get him into trouble

Is there anything we can do to explain to him that as he gets older, people will expect him to give them space - or will it come in it's own time?