What I've learned over time is that you will never feel "ready" to start a project, no matter where you are with your art. You'll just keep putting it off until you feel you've hit this specific point of mastery but that point is illusory because we as artists are going to be improving our entire lives. If you start now, it might not be perfect, but it will give you the opportunity to improve and get it to where you want it to be--you'll be practicing by DOING. Then the next time you do a project, you'll be even more prepared.
We do things so we can learn, how else can you learn if you don't do it?