Dude, the idea on the surface is not a bad one. I did something like that myself. But don't destroy your future. Finish HS and THEN get your freak on. Getting a GRE is no picnic and without it you'll be working at the drive-up window the rest of your life. At least if you finish HS and then do your thing, you'll have options available to you. You can do college or at least get a job that requires you to be able to read.

I did my freak thing for about 2 years, but after HS. When I had everything worked out of my system, I went to college and got an engineering degree. I had to pay for it myself and it took 7 years, but it was worth it. My best bud in HS got married as a senior and didn't finish. He now has 3 kids, works at a gas station, and has no time or money to go after anything better. Think he can afford weed?

The only thing bad about your plan is the timing. Finish school, then move to austin and don't get caught! Enjoy it while you can, because as you get older you won't get another chance. Just don't screw your future.