Adjustment of Status - I-485

Hi guys just here to update my timeline and I got one question I know somebody can help me here.

08.22.2015 sent all my package I130, I485,I131,I765 express mail
08.24.2015 delivered
08.28.2015 got sms notification case received
09.03.2015 got receipts by mail
09.13.2015 rfe told me to send again I864 for the petitioner/sponsor who is my wife
                     I sent it with my package but seems like I used old forms and asked to do it again with updated I864 form
09.16.2015 sent response to rfe
09.18.2015 online changed to rfe received and case reopened.

Now something strange, I didn't receive yet my biometrics apt letter
But just this rfe is that normal or I should receive first my bio apt letter before any rfe
when should I expect to receive this bio letter? I'm applying from Dallas tx

Thanks again for your help.