RE: How Long(Feild Dress)???
It's very important to field dress as soon as possible. The reason is the heat. You've got to get it out! The heat is what ruins the meat.
As for learning the procedure, I was lucky enough to watch a video a few times before even going hunting for the first time. Then there was someone to to guide me as well. Buy a video. Best way to learn.
Personally, I didn't go deer hunting until I knew I could gut the deer. It's a part of the experience.
Good luck.