A quinceañera is the kind of moment people remember for decades, and also the kind that quietly costs five figures once you add up the hall, the dress, the photographer, the band, and the food. The good news is you have a longer runway than most events: real quinceañeras are booked 12 to 18 months out, which means the spending does not all hit you in one month.
The trick is matching that runway to how you actually pay. Stretch the big, predictable deposits over the months you have, and leave the smaller last-minute stuff for the final stretch. That way nothing surprises your bank account, and nothing surprises your family either.
The 0% window is a deadline, not free money. If any balance is still on the card when month 18 ends, interest starts accruing on whatever is left at the standard rate, and it compounds. The plan only works if the balance is paid to zero inside those 18 months, so set the payment, automate it, and treat the payoff date like a hard date on the calendar.