With a little planning you can save on airfare. A study of over 500 million airfares showed that, in general, booking a domestic flight 49 days ahead of time is optimal for saving money.
Fortunately you don’t have to get OCD about it, the average price doesn’t rise dramatically until about two weeks before the flight.
Booking too far in advance will cost you extra too.
Flying on Tuesday or Wednesday will save you money – but it doesn’t matter when you book the flight.
I said “in general” because there are exceptions. With busy travel times like holidays you need to book farther out – the article says 96 days prior was optimal for Thanksgiving 2012.
With international flights, being spontaneous might get you the best deal.