Back in art school I took a class called Clothed figure drawing 1.
The class was great and so was the instructor. The problem was that I felt
I wasn't being challenged enough. I'm not saying I was better than my fellow students.
Let's just say I had more confidence in my stroke more than anybody
in the class, which has no bearing in skill level. I didn't doubt myself; which lies the problem.

Taking that class was like playing Madden in
"All Pro" mode. It's not easy, but it also didn't excite me.

I wanted to play in All-Madden.

So I brought this up to my instructor. He  then helped me  get a meeting with the department director to see if I could take a  more advanced class.
We get to the meeting and the director looks at my portfolio. It didn't particularly tickle his
fancy aside from a few pieces. Let's just say I didn't get to move up to a more advance class.

Guess what I did after being told no after that  meeting, I attended drawing/painting workshops only meant for advanced students. I also sneaked in on a couple of clothed figure drawing III classes. All this while putting forth the bare minimum in my class and still getting an A(which by the way proves my point).

Point of the story is, don't wait until you're ready. That day will never come. Sometimes you need to test what your limits are. Do not let anyone set them up for you.