Nico,
I recently did what you are contemplating doing. This is something I've wanted to do for over 5 years. I was an energy trader at a top tier English I-B. During this time, I've paper traded, read numerous books on the mental side of trading, on trader stories, on systems etc.., tried to over optimize and develop mechanical and automated "systems" and even opened a small prop account in my girlfriend's name(compliance) and traded remotely during my "spare time". I blew that account up in a few months. However, I knew this will always be something I wanted to do. If I didn't, I would always wonder what might have been. It's like that really attractive girl in high school or college that was nice to you but was nice to everyone and you never gathered enough courage to do anything about it and find out for sure. Well, I finally decided that I've learned enough sitting partially on the sidelines. I needed to finally ask coach to put me in the starting lineup. So my advice is that if you're confident and have put in the time and you know this is something you want to do then go for it. Ask yourself what's the worst that can happen? If I fail, then I would answer a question that has been lingering for a long time and then go back to wall-street and get another trading job. I'm sure you can do it too if you already have the experience.
Good Luck.