Picture the street blocked off, the folding tables lined end-to-end, and the guest of honor actually surprised when everyone yells. Throwing a retirement block party over a holiday weekend takes some coordination, and the costs for food, tents, and permits add up fast before anyone even shows up.
Timing is everything here because holiday weekends mean higher demand and earlier sell-outs for rentals. You want to lock down the big stuff early so you aren't scrambling, while leaving the smaller grocery runs for the week of the event.
That 0% period is a deadline, not free money, so make sure the balance is fully paid off before the 18 months are up or standard interest kicks in on what is left.