Best time for buying flight tickets in China

Hello there!

I want to buy a flight ticket from Shanghai to Harbin on January 24th (2015). However, at this time (November 26th), I think the price is to high (it is not a holiday in China or even a special day for having such high price). I heard that in China it is better to buy the tickets in only one or two months in advance, because at this time they are cheaper.

Is that true? When is the best time for buying flight tickets in China?

Thank you so much!

Sam