DS was in childcare at 13 months and playing with others by 15. He has become a lot more aware of other children and able to play now.

Sharing... I've seen a 2yo's version of sharing. (Put your cup down and swallow the drink now.)

See a child play with a toy.
Want the toy.
Take the toy.
Tell other child "Share!"
Run off knowing you're in the right.

I think about late2-early3-ish they start to need friends and stuff like that, but early childcare isn't detrimental - so long as you get the right one!