(NEXSTAR) — Holiday travel can be expensive and stressful, but you can save some money on airfare if you book your flight far enough in advance. 

Google crunched some numbers and found that travelers looking for cheaper Christmas flights should consider shopping around now. 

If you’re planning a trip for mid-December, you’re most likely to find some of the best deals on airfare in early October. According to a recent report from Google Flights, average prices for domestic flights tend to be lowest 71 days before departure.

Using Google’s insights, a good time to purchase tickets would be from Oct. 13-15 if you want to fly from Dec. 23-25. 

That’s quite a change from Google’s findings last year when prices were lowest just 22 days before takeoff.  

Similarly, travel-booking app Hopper suggested travelers book their Christmas flights before Oct. 14 this year.  

“Airfare will remain low, but volatile (moving up and down day to day) through early October, before rising in the weeks leading up to Thanksgiving and Christmas,” wrote economist Hayley Berg in Hopper’s 2023 Holiday Travel Outlook report.

The 71-day suggestion isn’t a hard rule, though. You may still be able to find a bargain by booking your flight between 54 and 78 days in advance, according to Google’s analysis. 

Also, Google previously noted that waiting to purchase your ticket on a certain day of the week isn’t really necessary.

“If you shop for flights on Tuesdays, Wednesdays, or Thursdays instead of Saturdays or Sundays, prices have only been 1.9% cheaper on average over the past five years,” wrote James Byers, Google Flights group product manager in a 2022 blog post. “So if your trip is just a couple of weeks away, don’t wait for Tuesday to roll around.”

While the low price window changed from last year, Google said other travel tips it shared in 2022 are still relevant today — like taking a layover or avoiding weekend departures to save money on your next flight.