How do I change the Invoice Due date to show "On Completion"?

[GoldStandard]

I run a home improvement company. We take payments Half down, Half on completion. The only way that I have found to show an invoice with a deposit is date-specific. How can I change the verbiage for the final payment to read "on completion", instead of "March 23, 2019" (for example)?

[ACAcatering]

At this point, I don't believe that is an option.  I would use the "Message" section to spell out when final payment is due in your case.