Vietnam is about hot bowls of pho on plastic stools in Hanoi, strong iced coffee in the shade, and quiet mornings on the green water of Ha Long Bay. You want to aim for the shoulder months of March or September to miss the heaviest rains and the worst of the summer heat while still getting good weather across the whole country.
A typical trip runs about $2500 once you factor in flights, places to sleep, and all the noodles you can eat. Splitting that chunk of cash into smaller payments makes it easier to handle, especially if you use the Citi Simplicity® Credit Card to spread the cost over time.
That 0% intro window is a deadline, not free money, so make sure you pay off the full $2500 before those 18 months are up or standard interest rates will kick in on whatever is left.