One of the most popular questions asked of travel experts is: “When is the best time to book a flight?” That answer is a revolving door of conditional circumstances, destinations, and seasonality patterns. But there is another all-important question. When is the best time to book an award flight? That is another tough question with its own loaded answer that depends upon your elite status with the airline, where and when you’re traveling, and in what class of service you’d like to travel.

There are two schools of thought on this subject. One is to book early to grab award seats before anyone else does. But, again, that always depends on the route. Many airlines withhold seats until closer to departure time, when demand for the flight can be better predicted. Some flights might see a flurry of award seats open up at the very last minute; others might see them earlier.

The frustrating answer? It all depends on many variables, but this handy calendar can serve as a guide for how to best approach optimizing use of your miles for air travel.

T-330 days before travel. This is when airlines typically load flights into the reservation systems so that people can begin booking them. If there are any award seats to be had from the beginning, this is a great chance to nab them. The sweet spot could be for brand-new routes where airlines have little historical data to give them an idea of potential demand, meaning they may be willing to open up more award space to promote the new route.

Between 11 and two months before travel. There may not be much movement during this extra-long period because airlines may still be willing to take the risk that more people will pay for these flights. People typically book flights within 30-90 days before departure. This means that when flights are loaded into the reservations system, they may look empty for months (and even weeks and days) before departure. Travelers seem to be an indecisive bunch and wait later to book a flight, which is why there can be fluctuation in seat assignments and prices closer to departure.

For holiday travel, people are more likely to book flights in advance instead of waiting until the last minute—much more so than the rest of the year. Also, airlines know that flights will be full so it is much harder to find a “saver” award seat at the lowest mileage price during these periods. You can always fork over 200-400 percent more of the price of an award ticket if you absolutely must travel on a particular flight, but this is rarely a good use of your miles.

An excellent tool to use when searching for award travel is Expert Flyer, which allows you to both search award space and set up an email alert when an award seat on your preferred date and flight opens up. This will save you time from checking websites and calling airline reservations numbers constantly.

You’re getting nervous because it’s 30-60 days before the trip. This can be decision time for many people. You’re facing the daunting task of firming up hotel plans at the destination and confirming the exact dates of travel with companions, but also waiting for free seats to open up.

During this window of time, you may start to see some flexibility while airlines make more award seats available. This is a good time to keep checking back for a good deal.

Keep in mind: Airlines love to squeeze every last penny out of a traveler and will begin to start charging fees for booking award travel close to departure. Typically, airlines impose a fee on award flights booked within 21 days of departure, but United took a flyer-unfriendly stance recently and began imposing fees for award travel booked within 60 days of travel using Mileage Plus miles. Many of United’s own elite members are even charged fees, which are typically waived in appreciation for loyalty. Beware the greedy fee.

Three weeks before takeoff. This is when airlines, other than United, start to kick in their greediest of fees. Elite members are typically let off the hook (except at United) when it comes to close-in booking fees, but be sure to know your status level. Delta is the lone holdout that allows you to book award travel at any time prior to travel without penalty with one caveat: no changes or cancelations are permitted 72 hours before departure. This time period, however, is when award seat availability might become more flexible.

Is first class easier to find? The holy grail of redeeming miles is extracting that top value for a premium cabin seat. But because there are fewer of these seats on a plane and they carry a higher profit margin for airlines, they may be harder to obtain in advance.

Airlines like Lufthansa won’t even make them available for redemption via partner Star Alliance programs (like United Mileage Plus) until two weeks before travel. If you’re willing to wait until the last minute, there might be low-hanging fruit waiting for you. But, then again, there might not; it’s all a gamble!

Ask an expert. If you don’t want to bother with the confusion, ask an expert to help you book travel through services like Book Your Award.

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