How long before you meet your SO family??

I'm currently in a long distance relationship with a guy!! We've been dating 6 months!! But work commitments make it difficult to see each other as much as we'd like!! This is his first relationship after a bad relationship!! I haven't yet met his daughter or mother!! I'm taking it slow and understanding with him but I'm wondering how long before I should be expecting to meet them?? Should I ask him?? This is all new to me and I'm just looking for some advice!!