As I mentioned in this picture, I first drew the TF victim as human before making the proper alterations. But along the way, I figured it'd be fun to do a before/after picture. And this is it. :)

Differences:
Percentage-wise, I'd say he's close to 50-60%, if that. The biggest change off-hand is his new tail, not too far along, with its tip ahead of the sprouting fur, far enough that you can easily tell what he's turning into (if you're looking at the colored image). His tail has also wound up pushing his boxers down a little, due to it having no tailhole. His left hand has mostly-finished claws and pawpads, his right hand only starting to change. His nose has begun to upturn, one of his teeth has grown long enough to be easily visible, and his left ear has slid up close to its new position and shape, his right ear not so much. His right leg is more or less finished, and much of his body has been covered by fur. A couple other things only seen in the finished picture, his hair is turning white and the white stripe on his forehead has begun to appear. Only place that hasn't been effected yet is his left foot, but that will quickly change.

Apologies for the messy look of the left image. The lineart was still light at the time, and this is the best scan I could get after many attempts.