How often should I talk to the girl i'm dating/like?

I started dating a girl and I don't want to seem needy or possessive but I want to talk to her and progress things. She is always on msn and on her phone. I'm on msn quite a bit but i don;t want to bombard her with messages yet I don't want to seem like I'm purposely ignoring her. I'm probably overthinking but what would you say is the right balance?