A study by CheapAir.com has found that this is the "prime booking window" when it comes to bagging the best price on your flight.
They shared on their website: "We now come to the 'Prime Booking Window', occurring three weeks to four months in advance, and otherwise known as the best zone to nab a bargain. Hunting for cheap airfare? Focus your efforts here. Its not as though you won't see fares change in this zone but fares average within five percent of their lowest here, and you're most likely to see a cheap fare pop up."
Any flights booked under three weeks and over four months before you go on holiday is considered to have a more premium price.
The 'Peace of Mind' zone is between four and six months before the date of flying and is the best choice for those who don't mind spending a little more to secure the exact flight they want.
They added: "We call this zone 'Peace of Mind' (122-168 days before travel) because it alleviates travel anxiety and will cost you a bit less than 'First Dibs'. If paying around $20 more for better flight options doesn't spook you and you're not much of a gambler, 'Peace of Mind' might be just the ticket. You'll lock in flight dates and still have a decent number of flight and seat options from which to choose."
When you move two to three weeks before you fly, the 'Push Your Luck' zone can offer you a good deal but availability may start to become more limited.
They added: "Like to gamble? Miss your chance for the 'Prime Booking Window?' If this is your scenario, the next option is the 'Push Your Luck' zone (2 to 3 weeks before travel). This close to your travel dates, the fares usually climb and a lot of the aforementioned options are selling out. However, there are pockets of luck in this zone.
"We can't make you any promises but some of those lower fares may still be available. Go into this zone with eyes open - Christmas week and popular high season destinations do not have the best odds. Less popular destinations or shoulder/low season travel might be a better risk. But be warned: even though sometimes the fare might not be that much more than if you had booked earlier, the same might not be true for seat options.
"Most airlines only offer a limited number of seat assignments for free; the rest of the travelers have to pay more to guarantee an aisle or window. The later you book, the less likely those free seat assignments will be available. Of course, you can always let the airline pick a seat for you for no charge, but if you care where you sit, this is something to consider."