GST on input credit of bills related to FY 2017-18 can be taken only till return for Sep-18 which is already over. However the GST council in its council meeting held in Dec'18 has assured that GST input credit of bills related to FY 2017-18 can be availed in GSTR-3B till Mar19. Eventhough as of now no notification was issued on this, you can avail input credit and keep track to verify notification or else wait till notification is released and avail in next month GSTR-3B