There is nothing quite like having a raw bar set up right in your living room for a weekend celebration. You want to lock in your date a few weeks ahead since good shuckers book up fast for Saturday nights. Getting the logistics right means balancing the deposit with the final catering bill.
A typical mobile oyster setup runs about $850 in the US, which is a hefty chunk to drop before the first shell even cracks. Spreading that cost out makes it much easier to digest alongside your other party expenses like booze and ice.
That 0% window is a deadline, not free money, and if you still have a balance left when those 18 months are up, standard interest will kick in on what you owe.