When traveling on a budget, every dollar counts. Unfortunately, the cost of airfare alone can burn a serious hole in your wallet. Don’t let that stop you from taking your dream vacation, though. According to Jeff Klee, CEO of CheapAir, there is a “sweet spot” to getting the biggest bang for your buck. Watch out for these signs that you’re paying too much for airfare.

“The most important rule is fairly obvious: don’t wait until the last minute, as that rarely works out,” he said in a statement. “But beyond that, you also want to be careful not to buy too early.”

Still, that’s easier said than done. Finding the most cost-efficient time to book is tough. Luckily, somebody did the math—so you don’t have to. Data crunchers from the online travel agency CheapAir surveyed over 917 million fares to determine the day with the cheapest rates.

Here’s what they found: While prices tend to stay the same between 320 and 106 days before a trip, they start dropping at the 105-day mark. Read up on these travel secrets to always get the best airfare possible.

That said, you might be tempted to book the moment prices drop. But hold up! You’ll save even more money by booking precisely 70 days before your trip. According to CheapAir, you can save a whopping 48 percent of the ticket’s total cost by using this trick.

After that date, airfares will begin to increase again. And don’t even think about booking any later than 20 days ahead of time, as prices will be soaring.

So, what are you waiting for? Start planning your next dream vacation, and book accordingly. Your wallet will thank you—guaranteed. Plus, here are even more secrets to traveling cheap, according to travel agents.