You want to celebrate the grad without stressing over the setup, which means looking at the calendar right now. Spring semester fills up fast for local rental companies, so the real trick isn't hunting for coupons—it's booking tents and chairs before the rush hits.
We are looking at about $900 total for a solid backyard setup. If you split that across the spring, you can get everything locked down now and pay for it in small chunks instead of taking a massive hit all at once.
That 18-month intro window is a deadline, not free money. If you still have a balance left on the Citi Simplicity® Credit Card when those 18 months are up, regular interest kicks in on what is left over.