Aim to book 15–30 days before departure for the best rates. Prices typically bottom out around 44 days out for broader U.S. travel.
For Thanksgiving and Christmas, the "book-by" deadline is typically October 31st . Best Day And Time To Buy Plane Tickets - Forbes
The most affordable window is often 8–15 days before departure for quick trips, though long-haul routes (like Europe or Asia) typically require 3–6 months of advance planning for the best value.
Planning your purchase within these "Goldilocks windows" is generally more effective than choosing a specific day of the week.