What? This makes no sense. You're doing it wrong. If you were really passionate about playing in a rock band, you would already be filling your time playing in a band, jamming on weekends, playing in your free time.
You don't just "go out and start" doing something you are passionate in. If you are passionate about it, you can't stop doing it.
What do you do in your free time? You have no hobbies or things that keep you busy or wish you were doing rather being at work?