Rename scanned in invoices

How would I set up a rule to take scanned in PDF invoices, and rename them to contain their date, and invoice number in the file name?

So far, with MacSparky's help I've got a rule that will rename the file with the date printed on the invoice, but I'd also like to add the invoice number, this number is in the top right of the page and is formatted "INVOICE: 5981868" the number is always completely different on each invoice (but contains the same amount of digits). Is this possible?

Yes, use a custom text token instead of a date one. You can set it to match a specific or any number of digits.