No. You cannot change date for opening voucher.

It is only possible on book beginning date. Whenever you will enter opening stock or opening account it will take default voucher date same as book opening date whether it matches with present date range of SW or not.

Opening Voucher Date  =  Book Benign Date

More info :

• http://www.rancelab.com/help/fr6_location_master.htm
• http://www.rancelab.com/help/fr6_openign_balance.htm