That’s correct, however the double entry for the bank opening balance would be posted to suspense (9998). Typically what you would do is journal this balance out of suspense into the appropriate nominal codes.
Let’s say I start using QF halfway through the year and I have a bank opening balance of £15,000. This £15,000 relates to the sales made in the first half of the year. When I enter the OB it would debit the bank and credit suspense (suspense is just a temp holding area until it’s properly explained). Now I need to journal that balance out of suspense into General Sales (4000) or a sales code of your choosing, only when this has been done will it affect the P&L.
Hope that makes sense!