If you want tix for peak times, you might just get the best deals at 330 days. For example, you want to fly the two most popular times over thanksgiving week: the airlines all know that they are definately gonna sell all those tickets, so there is no reason to discount them now or later. Having you buy your tix at 330 days may get you a better deal than booking later, as the airline will have use of your money for that much longer (more money they won't need to pay interest on which is a great thing for them).
In all honesty, unless you are booking frequent flyer tix for popular times, or you are booking on a discounter (say JetBlue or maybe Delta/Song, or SouthWest, where they sell the cheapest fares first), you are probably better off holding on to your money until later.
All this being said, we booked our tix for April school break at 330 days, but two of our four tix were frequent flyer awards. Still, I now wish we had held out for JetBlue to announce fares, as JetBlue would have cost about the same (in total for the 4 tix), and not used up our SkyMiles.