It depends on your trip:
If you want to travel during peak season like Christmas and New Years, book as early as possible, especially for long routes like USA – Australia.
If you want specific dates, especially weekends, and you are picky about airline choice and itinerary, book early – 6 to 10 months in advance. This usually will ensure you get great savings and itinerary that you want.
If you are very flexible with travel dates and airlines we have fantastic deals on short notice of 7 to 30 days. Such fares will have discounts as much as 70% off as regular fares are very high closer to departure.
If you want to travel in the summer, book your tickets in fall. Yes, that means 8-11 months out. Summer is the busiest season and airlines will release just a handful of amazing deals on great flights very early in advance. The closer to departure the fewer good discounted options there will be to top destinations.