Japan is all about the details, from the quiet precision of a tea ceremony to the chaotic joy of a late-night ramen stall in Osaka. Booking six months out lets you grab the best flight prices and lock in reservations at the restaurants you have been dreaming about.
If you need some breathing room to pay for the $4000 total, you can use the Discover it® Cash Back. It offers 0% intro APR for 15 months on purchases and balance transfers, which lets you pay for the trip in smaller chunks without paying interest during that window.
Remember that the 0% intro APR is just a window to pay off your balance interest-free. If you still have a balance after 15 months, the bank will charge you interest on whatever is left, so treat this as a strict deadline.