when to find cheap airfare?

What’s the cheapest time of year to buy airfare for travel in early January 2017? Thanks, Bob

Terry Says:  Interestingly, the Wall Street Journal just posted an article on the subject, which I found fascinating.  Here is a link to the article.  But you must be a subscriber to read it in full.  It mostly focuses on what day of the week is the time to get the cheapest seats.  But here is a sentence from the article that might be helpful:  ” The sweet spot is about two months before departure. The study found the lowest-priced economy tickets for a flight within North America were sold, on average, 57 days before departure.”