Turning 30 deserves a great meal with your favorite people. It is the kind of event that requires planning ahead to make sure you get the room you want without feeling the pinch all at once.
You have a three-week window to lock in your spot at a restaurant. Use this time to organize the guest list and set your budget before the bill arrives.
That 0% window is a deadline, not free money. If you have a remaining balance after the 18 months pass, you will start paying interest on whatever is left, so stick to your payment plan.