You are finally settled in, and the friends are coming over for drinks and finger foods. A casual night still adds up fast when you are buying groceries and bulk beverages for a crowd.
Lead-time is your best friend here. Since these are deadline purchases, you want to know what to stock up on early and what can wait until the week of the party so nothing spoils.
That intro window is a hard deadline, not free money. If you still have a balance left when the 18 months run out, standard interest kicks in on what you owe.