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.