As per my understanding, we need to file 3b by August 20 which is a summary return. After that we need to file gstr 1 by 5th and gstr 2 by 10th of September
Online return of GSTR 3B now avialable but there is no any offline utility for the same. it may also possible cosolidated data we have file online only by logging to the gst.gov site.