Roughly 57 days in advance. Booking within this window can save approximately 10% compared to the average fare.
Aim for 176 days (about 6 months) before departure for savings of roughly 11%. best day to buy airline tickets 2016
According to the , the ideal timing depends heavily on your destination: Roughly 57 days in advance
The sweet spot is approximately 77 days out. Best Days to Purchase vs. Best Days to Fly best day to buy airline tickets 2016