This is exactly when to book a flight for the biggest savings, according to travel experts

I have the worst luck with getting great deals on flights. Knowing full well the best time to book a flight, I recently postponed purchasing an airline ticket by just 12 hours, and within that time, I saw the price jump not once, not twice, but three times by the time I got the confirmation needed to hit “buy.” Just when it doesn’t seem like there’s any secret formula to scoring the biggest savings on airfare, some travel experts are coming through with the need-to-know tricks and tips on when to bite the bullet.

When it comes to booking flights, you basically have to go about it Goldilocks-style. If you purchase your tickets too early or too late, you’ll get burned. But there’s a prime time backed by data that guarantees the most bang for your buck.

“While everyone knows there’s such a thing as booking too late, what’s surprising is that there’s also such a thing as booking too early,” said Patrick Surry, Hopper’s chief data scientist, in a press release. “Flights go on sale 11 months before departure, but don’t expect to catch deals more than 150 days prior to takeoff. Booking more than six months ahead can cost you since airlines set their initial prices conservatively.”

“Booking more than six months ahead can cost you since airlines set their initial prices conservatively.”

While it’s a good idea to start tracking your prices three or four months in advance, it’s hard to tell when to pounce since airfare fluctuates 5 to 10 percent within a single day, says Surry. (Pretty sure we’ve all learned this the hard way.) Prices tend to be highest the two weeks before departure, reports Travel & Leisure. Buying your ticket three weeks in advance is the sweet spot. It seems pretty late in the game—especially for those of us who love to plan ahead—but it certainly pays to be patient.

Now that you know the best time to book a flight, time to prepare for air travel: Steal Meghan Markle’s hack for flying bloat-free and keep this workout on hand to work your muscles after you land.