To me, up front means before work starts.
To me Paying "Up Front" means paying when the account is handed over immediately the work has been carried out.
Payment in "advance" means before the work has started.
Both of which do not convey confidence in the type of workmanship carried out to the customer,
My opinion is that the customer should be able to ensure over a reasonable period of time all work has been carried out satisfactorily before payment.