Hi siska72,
Welcome back out to Community. This is a great question! With QuickBooks Online you want to ensure you're tracking your transactions accurately. I'd be glad to help!
As you've mentioned, your sales need to be recorded for January, when they take place and your reports also must be accurate. There'll be times when customers may not send payment until a future date, but you can still manage and reconcile your accounts with these transactions, regardless of the date of the invoice. The key is to match the amount paid, with your bank account. This is for reconciliation purposes and not so much tracking sales. So, when you Receive Payment on an invoice, this is where you'll enter the date the payment hit your bank account, in accordance to your monthly statement. The date the sale took place will remain intact.
I hope you find this to be helpful!
For additional questions and concerns, please don't hesitate to reach back out. We'd be happy to assist!
