The dates would be worked out by a committee of officers and not yet finalised. So dont wait for that and i suggest you to file GSTR-2 for july-17 before 30th November 2017.
we saved all data of GSTR 2 in online mode for the month of july 2017, but now GSTR 2 is not available on portal ,which would be submited by us on or before 30th nov 2017
Please check the notification in the GST portal. GSTR-2 removed from the portal after 23rd meeting of GST council. SO it is confirmed that no need to file GSTR-2 for July17 to Mar18.