On 28th Day of Lunar 9 Month (農曆九月廿八日), it is considered as the Manifestation Anniversary of Heavenly Marshal Ma Hua Guang (馬華光天君).
For Year 2014, it falls on 21 Oct, a Tuesday.
For more info on Heavenly Marshal Jiang Xian Guan, you can proceed to the following links:
Introduction of Heavenly Marshal Hua Guang of 36 Heavenly Generals (三十六天將之五顯華光馬天君):
Introduction on Mountain Hua Di (華帝山之簡介):