Approved, what else?

I just found out online that the I485 application for both my hu*****and and I were approved last week. I'm very happy. The application was made under NIW almost 3 years ago.

Our current status online are "This case has been approved.". But I'm wondering whether that's all, because I saw others talking about interview, REF and so on and we were never asked to do so. I'm pregnant and my hu*****and will have a long meeting two weeks later. Does anybody know what I should do now for interview and/or REF? What does "Approved" mean?

Thank you so much in advance!