A Sunday brunch is a smart way to celebrate while keeping vendor costs lower than a typical evening dinner party. Focus your energy on the guest list and menu early, so you have plenty of time to lock in your catering deposit before the big day.
Since this is a fixed-date event, you need to manage your cash flow carefully. Break the total cost into manageable chunks so you aren't stuck with a massive bill when the event ends.
The 18-month window is a deadline, not a gift. If you haven't paid off the $1600 balance by the end of that timeframe, the card will start charging interest on the remaining amount.