Best day to shop: FareCompare’s data shows that best time to book a flight in the U.S. is Tuesday at 3 p.m. eastern time. This day and time give you access to the best flight deals. It’s when airlines release the most sales and the best time to book plane tickets. Learn more about this here. Best time-frame to shop: This varies depending on where you fly. 1  Domestic fares: The best time to buy airline tickets in the U.S. is between three months and 30 days before departure.