You want to celebrate your engagement with good food and your favorite people at a local park. Park pavilion reservations open months in advance, and those weekend dates go fast, so timing is your biggest lever here.
A full setup with catering and park permits usually runs around $3,000. You do not need to throw that whole amount at your bank account all at once if you plan the timeline right.
Just remember that 0% interest is a temporary deadline, not free money. If you still carry a balance after the 18 months end, the standard interest rate kicks in on whatever is left, which makes your party a lot more expensive.