Late winter is the sweet spot for Oaxaca. The holiday crowds thin out by mid-January, the dry season settles in, and you can wander the smoke hall at Mercado 20 de Noviembre without fighting for a stool. You go for fresh memelas, deep moles, and the massive Sunday market out in Tlacolula.
A solid week runs around $1750 from the US with flights, central lodging, and endless street food included. Instead of draining your savings upfront, you can spread that cost across a year and a half without paying interest if you set it up right from day one.
Keep in mind that an 18-month 0% intro period is a firm deadline, not free money. If you still carry a balance when month 18 ends, the card's regular variable interest rate hits whatever is left, which defeats the purpose of planning it out.