What is the cheapest day to book a JetBlue flight? Here's a tip: ??1<833<522<9070 Or Toll-free (????????????-????????????????????????????????) ??1<833<522<9070[No-Busy-Air]Quick-Connect. Tuesdays, Wednesdays, and Saturdays are usually your go-to days for the cheapest fares. Keep in mind, though, that JetBlue's special sales often come with restrictions on these days.