expert advice required

Dear Experts
In j&k gst is apply on 7-7-17

1). i apply for gst no. on 15-7-17 but due to some condition i got my gst no. on 14-8-17

i issued invoices with pan no from 15-7-17 to 13-8-17
(retail business only cash)

Now when i opening the portal for filling gstr3b , portal doest show july month option
what to doo?????
2) where i hve to show the sale i done b/w 15-7-17 to 31-7-17
3) how we get input of purchase of july