Historical advice to book at midnight is largely outdated as pricing is now continuous across all time zones. A 2015 study found a 6% saving at Tuesday midnight, but this only applied to roughly 1.6% of markets. More Effective Savings Strategies

The day you and how early you book have a significantly higher impact on price than the time of day you hit "purchase".

Mid-week evening bookings sometimes yield better deals for leisure travelers after the heavy volume of business bookings during the workday has subsided.

The idea of a single "cheapest time of day" to buy flights is largely a . Modern airlines use sophisticated dynamic pricing algorithms that update fares in real-time based on demand, seat availability, and competitor pricing rather than a fixed daily schedule. The Reality of Booking Times

Some research suggests booking very early in your local time may catch overnight price adjustments before algorithms readjust for daytime demand.