We are yet to file GSTR 3B rtn. for June and July 2020. While the last date for filing is 23rd Sep and 27th Sep respectively, shall we file 3B rtn. for Aug now ( before filing 3B rtn. for Jun and Jul ) as the last date for Aug 20 is 20th Sep 2020.
17 September 2020
You can do it .There is no bar on filing those months.Since every month is independent.
But for ITC purposes and practical issues ,better to file June & July and then August.