I have to say I was somewhat surprised that he made it to sergeant and earned his good conduct stripe, given that in 1916 he was getting into trouble on a fairly regular basis. Must have some sort of conversion, or got married - in my experience young soldiers getting married can result in major changes to their attitude and behaviour. Given that he's wearing his medal ribbons and sergeant's stripes, I would say this photo was taken in 1919 shortly before his discharge on medical grounds