I agree with this wholeheartedly, but I still have yet to take the leap ): I'm not afraid of sucking anymore, but I know have to use my ear a lot more.
I've been playing piano for four years, flute for two or three, drums for about three, and guitar for about two months (consistently). To this day, I still use sheets or tabs to learn a song (with a few I've learned by ear). Though when it comes to getting remixing ideas for a song I really want to do, I play the song by ear.
As for making my own music, I started out using loops in GarageBand during my band class. Then I made loops at home since I had the software. Eventually it got boring since there were only so many loops. Around that time, I wanted to get into remixing and I had a keyboard with a USB cable, so I totally could have gone for it. I had joined the forum and everything, but then I psyched myself out and I stopped using it.
I took a class at my music program that introduced me to Reason, and I made three original songs. That made me want to start remixing, but I didn't have the software at home and I psyched myself out yet again.
Last year, I took a chance and started improvising. I was bad at it, but I knew my music theory, so there was no excuse to give up. That state of mind made me come back to the forum not too long ago, and recently finished a track I had started in February. (I couldn't finish it because I didn't have the Reason software until a week ago.) Once I get used to making more songs, I think I'll have more confidence to submit a remix.
So how long have I been making music? The technical answer is four years. If you mean originals and remixes, then on and off for a year or two.