My kids are 3 and 5 so right now the only activity we do is swimming lessons which are done in a group setting, but aren't really a team sport and the kids/parents in the class change constantly due to scheduling etc. I'm thinking next year once the oldest is 6 we will put her in some team sports.

My oldest has made a few friends in kindergarten, but so far we haven't really hung out with those kids/parents outside of a few birthday parties.