As others have said, aging on the hoof must take into consideration the factors of habitat, genetics and range conditions. However, noting you are in Austin and the background looks like Edwards Plateau habitat I am going to guess you're looking at a 2-1/2 year old deer. Could be 3-1/2 but I don't think so.
I base this estimate on the observations we can make of a thin neck, the lack of heft in the brisket area of the animal and the relative appearance of his legs being a bit gangly when compared to his overall body configuration. If I was on a property where my goals were the healthy development of the herd, as opposed to a pure meat hunt, I would let this guy walk this year for sure. On the other hand, that is a decision we each must make for ourselves and be comfortable with the outcome.