I don't think 6 months is such a long time for someone to get their life together; especially since that person has probably never lived out on their own before. It's easy for some of us to think it's simple to do, mostly because we know how to do it. A person of 19 most likely has little cash, no credit, no references to give. Finding housing isn't going to be simple for her, and setting up jobs with enough income to afford living out in the real world will be a challenge as well. I think the shock of being kicked out of her own family will be enough to make her think pretty hard about what the rest of her life will be like.
Kim, more power to you. I'm sure you can 'keep things under wraps' for a while. Besides, it's good for your karma.