Here is one travel website's take on this burning question. Their takeaway?
If you're trying to figure out when to book, you're asking the wrong
question. The better question to ask is what day of the week is
cheapest to fly. And that means flying on off-peak days: Tuesdays,
Wednesdays, and Saturdays are often much cheaper days to fly
https://thriftytraveler.com/guides/best-day-to-book-flights/
I book when I feel like it.
Their takeaway worked years ago
the world has changed and thanks to dynamic pricing and rapidly updated sales information this time honored old advice is no longer fully reliable
If you have flexibility, it is worth checking various days of the week. At least on United, I often find that certain flights are less expensive than others, particularly if you are looking at premium economy. This year, I flew on a Wednesday because that was the day with the least expensive flight at the time I preferred.
Personally I know what I'm willing to pay, I follow United's pricing from Dulles and I'm OK having the belief that I think I have some kind of grasp of that movement.
And that means flying on off-peak days: Tuesdays, Wednesdays, and Saturdays are often much cheaper days to fly
I can be pretty flexible, I do shop by days, and looking back at my last 8 ticket purchases 3 where for flights on a Wednesday, 2 on Tuesday, 2 on Sunday, and 1 on Saturday. Is there truth to that statement? I don't know, I do find myself looking at flights on Wednesdays first, because I've purchased the lowest priced Premium Plus tickets for Wednesday flights, but I always scroll through the rest of the week and check all days.
When one checks prices, it may be the case that Wednesday is the cheapest day to fly on, but there are too many other market factors that drive price so that the so called cheapest day to travel changes. There's the tried and true supply and demand. Premium cabins vs. Economy cabins. Are we talking business routes or leasure routes or routes with a mix of both. Is it a seasonal route? What are the arrival or departure airports?
There are too many variables to make "flying on off-peak days...much cheaper days to fly" some sort of maxim that I would want to live by.
I fly overseas primarily on American and I do find Tues Wed and Thurs to usually be cheaper but every thing is variable. And then there’s the issue of maybe your flight is cheaper but if you do spend an extra day for a hotel stay maybe it’s not worth it.
Thrifty Traveler used empirical data to reach the conclusion that, for international airfares, 2-6 months in advance is the best time to find the lowest airfares.
Tuesdays, Wednesdays and Saturdays usually are the least expensive days.
I have to agree as that has been my experience flying from California.
