Thank you for posting here in the Community. I'd be glad to assist you with any questions you may have with creating a bill in QuickBooks Online.
When you run the reports within the QuickBooks system, the basis in pulling up transactions are the dates when you created them and not the due dates. You can record the bill and mirror them as to when you create the actual transactions.
It would still be best to seek expert advice from an accountant to ensure it'll not affect your reporting needs in the future. To learn more about the Source and Targets concept, I'm adding the article I recommend on this: