'A:  When to book flights is a question that torments even the most experienced travelers. Who hasn't sat in front of the computer wondering:  Do I wait for a better deal, or is this the best I'm going to see?
There are no hard-and-fast rules for hitting the right booking window. A recent report from online travel agency CheapAir found that, historically, the lowest average fares have been available seven weeks before departure. Airlines Reporting Corporation (ARC), which manages airline ticket sales for U.S. travel agencies conducted a similar study and located the best airfares six weeks prior to flying. But that window changes dramatically depending on where you are traveling – and when.

Winter Caribbean and ski getaways
There's no use waiting for fare sales here. High demand and limited airlift mean that prices for winter flights to Caribbean islands and smaller ski-country airports usually don't fluctuate much – and rise dramatically fairly early. Looking at last winter's economy-class fares from the United States to the Caribbean islands, ARC found the lowest average fares 21 weeks before departure. That jibes with CEO and cofounder of online research tool FareCompare, Rick Seaney's advice, to book both Caribbean and ski getaways about four to five months before your trip.

*BY THE NUMBERS:  $589 – Lowest average economy-class airfare to the Caribbean last winter, booked 21 weeks in advance. (Source:  ARC)*

Holiday travel
The earlier the better, once again. Last year, analysts with CheapAir tracked domestic airfares for more than 11,000 markets for Thanksgiving, Christmas, and New Year's travel. Notably, for all three holidays average ticket prices hit a low in early June. They fluctuated throughout the rest of the summer and early fall, but by the end of September they were steadily rising. Not everyone can plan a winter holiday in June, of course. But if you're considering going from somewhere cold to somewhere warm, Jeff Klee, CEO and cofounder of CheapAir, advises getting tickets as soon as possible. A similar principle is at work fro spring-break travel. Tickets to Florida and other popular warm-weather destinations start rising early – and tend not to vary. Seaney recommends planning these trips five months in advance. “Airlines are really good at knowing when an airport's local school districts are on spring break, and will adjust airfares accordingly,” he cautions.
Of course, all of these booking windows are estimates and should be taken as guidelines rather than than rule of law. As George Hobica, founder of Airfarewatchdog, says: “If there were an established best time to book, airlines would identify it and hike fares accordingly.” Consider yourself warned.'

Source:  Hastings, Mark. “How Far in Advance Should I Buy My Airline Tickets?” Travel+Leisure Feb. 2014:  48-49. Print.