Award seats are not like prices: they never go down. (There are a few exceptions, when an airline runs special promotions to persuade people to give up some of their miles on flights that fewer people than expected are willing to pay for, but those are rare and tend to happen at the last minute.) Airlines allocate a small number of seats per flight at their lowest mileage requirement level and make others available only for more miles. If you know when you want to fly, get on the airline site on Day 1 and grab seats in the first, low-mileage allocation before someone else does. You snooze, you lose.