A non-refundable retainer of 50% is due at the time of signing the contract to reserve their date (cash, cc, money orders, personal checks). Outstanding balance is due 2 weeks prior. I also think it's extremely tacky to track down the client during an event for them to pay up. Imagine following up with them an hour into the party (and they forget to write the check), until an hour before the end and this time they start avoiding you, then again right before they leave. It is a hypothetical situation, but it is still awkward... I'd rather save them face. Another reason I don't like taking payment at the event, is because that is handled by our office staff ONLY. When someone from your staff (who does not understand or quote packages) has a client hand them over $2,000 towards the balance on a DJ/Lighting/Drapery package, they might start thinking, "Hey I should start my own company!" Obviously they don't have any clue about what it takes to get 300 events a year, all they see is the green. In my book talent retention is critical, so I would rather cover all my bases and kill 3 birds with one early payment (getting burned on the payment, annoying the client by asking multiple times, loosing talents).
I won't lie, I have about 5% of our clients that would rather make their final payment the night of. I will make that accommodation and this tends to be on smaller packages. Now that I am thinking about it, I have NEVER had one of our larger packages question paying upfront (they will usually pay off their balances sooner). If someone is trusting you with a larger package, they:
a.) Know EXACTLY what they want
b.) qualify you hardcore!
c.) are too busy to worry about details due to their busy lifestyle
After jumping through a bunch of hoops you're now credible in their eyes, and it's all about sticking with your system and over exceeding expectations. IMO, a majority of our clients feel more comfortable going with us because we have a process for EVERYTHING. To each their own.
Another tip, don't accept wooden nickels.