Timing plays an important part. Specifically, plane tickets usually don't get cheaper closer to the departure date. Instead, flights tend to be the most inexpensive when you book between four months and three weeks before your departure date.
Is it better to book a flight early or later?
We've found that short-haul flights are more predictable when deciding the best time to book: the best time to book a short-haul flight is a few weeks to four months before departure. The price variations for short-haul flights are consistently competitive, especially for popular destinations.