Thanks for reaching out to the Community, queencitypi.
I'd like to share some insights about the PDF file in QuickBooks Online. The invoice date will start from the oldest to the latest PDF date. The date given to the PDF is generated automatically by the program and we're unable to change it.
For now, we'll take this as a product suggestion. I'd recommend visiting our Blog site for more information about the latest news and new product enhancements.
I've also included these articles on how to customize and import custom templates in QuickBooks Online:
Please let me know if you need anything else.