Age looks about right. I think you did a really good job in sculpting this. How did you get the uniform textrure? By impressing a textured surface?
My only minor critique would be that his right ear looking towards him doesn't match the left. I think you could improve it by slightly reshaping the lobe to be closer to the other side (and which is more realistic). You may also want to slightly reduce the depth of the forehead creases as they may look too harsh with paint. Not much wrong with your sculpt though. I look forward to seeing it with paint.
Colin