Being a free-spirited, spontaneous soul is a beautiful thing, but when it comes to booking your flights, being prepared pays dividends. While it's possible to score a deal on a Gassim Airport to Narita Intl. Airport (NRT) flight at the last minute, prices usually don't get cheaper as the departure date nears. Studies show that the sweet spot to book a domestic flight is between 28 – 35 days ahead. For international journeys it's between three and four months. You can also score some of the biggest bargains when airlines first release seats for booking up to a year ahead of departure.