Sort:  

A sketch really doesn't have a definition. Nor does it every really have to go past this stage. Most of the time it doesn't even have to be done on the same surface the final piece is going to be on. Most portrait painters will paint a "sketch" of their subject before starting the final. Usually a much smaller scale.

I agree however a lot of times with contests there are some rules set and I just wanted to make sure you were ok with it. Thanks for that :) you are awesome!