I believe that if you know your a good enough shot you can take whatever shot you know as in your limits.

As far as young does I took a young really young doe that still had spots in late December. Fawns around here loose their spots in early septemeber. I didn't know it had spots when I shot but I know the deer wouldn't have made in through the winter. If I had know I still would have shot it. This wasn't a farm setting with tons of food.