Buy your plane tickets 56 days before your flight at around 3:00 PM EST.
Studies have shown that business class flights, first class flights, and economy tickets are at their cheapest about 56 days ahead of the flight. Why should you aim 3:00 PM EST? The cheaper airlines, like Southwest and JetBlue, list their new sales early on Tuesday mornings. By mid-afternoon, the bigger airlines like American and United will have.