Total? Probably about 10 years, but that's counting guitar since I've been playing from age 11 or 12.

For just music production it's probably been about 2-3 years of varying degrees of seriousness. I like where I am now, I know I have a shit ton of work to do still to become "professional", but I can see my progress and it is a great motivator. Looking back at my tracks from two years ago really gives some perspective, I am pleasently surprised with myself.