I would like to leave from Guangzhou around September 15th, 2016, and go to visit Shaolin Temple.

The mid-autumn Festival, also called Moon Festival falls on Sep. 15this year and people will have three days off from work from Sep.15 to 17. If possible, avoid these days as the flight ticket will rise. Also, avoid national day holiday from Oct 1 to 7, when will be rather crowded at scenic spots.
The time period between the two holidays is great time for travel.

TY for the reply that's good to know, although i didn't word my question right i meant is there a martial arts festival at the temple.

Okay, I see! You can enjoy the martial arts show at 9:30, 10:30, 11:30, 14:00, 15:00, and 16:00. Have fun!