I'd say early 1910s, just before WWI.  The cut of the coat and the trousers, the high, stiff collar, the single-breast waistcoat and the enthusiastic moustache strike me as late Edwardian.  I'm no expert, either, just a keen amateur  

  But 
here is Wikipedia on 1910s men's fashions.  Very similar, IMO.  Certainly no earlier than maybe 1907, but I think more likely 1912-1914.