Before You Feel Ready
If you wait to perform a piece until you feel absolutely ready, you might not every get there.
To achieve great things, two things are needed: a plan and not quite enough time.
— Leonard Bernstein
Much like other things in life, perfectionism is really an excuse to not take action.
Very often you will fail your way to success.
Here is what I mean. When I was preparing to play Liszt's Totentanz with the university orchestra I scheduled myself a bunch of mini performances during the learning process for friends or whoever would listen. Some of these performances were awful but I learned what I needed to fix. I performed the piece when I didn't feel completely ready. When the real performance came I knew how I would respond under stress and I had the confidence to succeed.
Learning theory also concludes that memorization and learning work best if we test our learning before we are ready. For example take the quiz before the lecture. Even if we guess the answers or don't know at all. We then study and we are much more engaged to figure out the answers we missed. See my reading list.
I often do this with my students. I have them play their piece memorized before they feel absolutely confident they can do it. In the process of guessing some notes and making some mistakes they see where their holes are.
The usual path for students is the play their recital piece to infinity until there is no chance for mistake.
The problem with this approach is that the memory is often very fragile. It is only finger memory and they haven't engaged the brain to put it together.