Lock Date start new Invoicing in GST India

i would like to lock the date on 7 of this month for all my old account and start new invoicing with GST india Format. as my State Implemented GST on 7/07/17. i want my old balance to carryover in new format please help.

You do not need to do anything. Just start using new tax codes. If you want, you can lock transactions by setting a lock date: http://www.manager.io/guides/set-lock-date/5510.