While I don't mind getting final payment of day of wedding or, if the customer can't do that, I can wait for final payment before I edit but I do NOT recommed editing before final payment.

If you've edited and you haven't gotten paid, holding the video doesn't do you any good. You've lost time that you could have used for another paying project.

Whether it's a shoot or an edit, time is paid for BEFORE I begin that stage of a project.

This seems to be what you do Scott and I think that is reasonable and sound.