Hi there, @B71.
Since we're unable to advise on what you will use for a start date, I'd suggest consulting your accountant or accounting professional. They can guide you on what's the best way to handle this and provide more expert advice in dealing with this concern.
I'm adding our handy articles, it provides topics in managing your sales transactions in QuickBooks: Income and expenses.
If there's anything else I can help you with, don't hesitate to click the Reply button. I'm always around to help you out. Be safe.