Listed below is the list of the relevant dates to note:

Aug 20th GSTR-3B for July 2017
Sep 5th GSTR-1 for July 2017
Sep 10th GSTR-2 for July 2017
Sep 20th GSTR-3B for August 2017
Sep 20th GSTR-1 for August 2017
Sep 25th GSTR-2 for August 2017
Oct Normal Schedule for Return Filing