Conventional wisdom holds that Tuesday and Wednesday are the best days to book flights, but a recent study reveals Sunday to be the real sweet spot if you want to nab better airfare. 

According to research conducted by Airlines Reporting Corp., Sunday's lowest average airfare price is now $432, followed by Saturday at $439. Tuesday averages at $497, making it the best weekday to snag tickets. And according to Yapta Inc., a company that informs travelers and managers of ticket price declines, 21 percent of recorded price drops occured on Tuesday--the most of any single day--though drops continued throughout the week.  

So what's the deal with weekends?

Airline executives hike ticket prices at the beginning of the week, even as oil prices are dropping, the Wall Street Journal reports. The seats that don't go early will likely see a fare drop by the time Sunday rolls around. And thanks to social media, vacation shoppers now have 24/7 access to possible discounts, thus booking on weekends and keeping those discounts from business travelers, who tend to book at work during the week. 

Bad news for procrastinators: The ARC study also shows that you should book 57 days in advance in order to get the cheapest deals on domestic flights. And according to Hopper, a pricing analysis firm, the average shopper will spend 12 days lolling about before actually booking their tickets. (Sound familiar?)

If you want to get your money's worth, hold off until the end of the week to lock down your flights, but be sure to plan ahead. Says digital trends expert Gabriel Shaoolian, "Book early and do your homework. The [prevalence] of travel booking Web sites have made the dream of a last minute 'unsold seat' deal an extinct animal."

Another tip from Shaoolian: Make sure to include local airports in your research, and don't rule out flights with connections--particularly if you're cost conscious.