Is it okay to start drawing the hair first?

I tend to draw a lot, mostly weird little things meant to make my teachers smile when they see my papers. But when I draw people, I usually draw anime, I start with the hair design first and then the face and then the body and clothes. I was just wondering if it was okay to draw like this or not. I don't draw any like skeleton design first, I just draw the hair and then go on from there. I can basically see the head already there, it's just not. Just tell me if this is okay, I feel like it's wrong but it works.