I think you are not the only one j. Everyone wants to be an expert aging deer on the hoof, but there is very little chatter on jaw aging. There is a certain subjective degree of technique, but I read a QDMA article that lab testing is subjective as well.
I just noticed damn spell checker label the thread haw.
I skin out a lot of heads for my taxidermy friend. A good share of high fence deer that the ages are already known. The deer are in a 400 acre pen so the teeth wear is consistent with wild deer. I also shoot a lot of does, so I get to play more.
There is a ton of info on the net. I think QDMA has some pretty good tutorials. I would suggest you go there. You basically need diagrams to educate yourself.
I put together a jaw collection on a sting. I gotta get that back. I'd suggest you compile one, it's been a game changer for me. I have fawn to confirmed 6.5. Past 6.5 it gets very gray.