I've also heard that the best time to book a flight is right after midnight Tuesday/early Wednesday. Speaking as one who is interested in airfare logistics but is not a travel professional, I understand that sale fares are often loaded at that time, and reservations that were made with a hold over the weekend and on Monday but not ticketed are cancelled at that time. I believe that this means midnight Eastern time for all North American airlines; I suppose that for airlines of other nationalities it would be midnight in their headquarters' time zone.

Andrew Missouri