Been on it several times myself, mostly when I was younger. I get the impression that you have heard some of the negative things about it that are giving you cause for concern. Personally, I think that most of those concerns are complete hogwash. The only physical downside I suffered was a lot of dryness and that is to be expected. For me it was one of the best things I ever did for myself and even without knowing you, I think you will find the same thing if your acne was as bad as mine when I started. My only regret is that I didn't have the Accutane option sooner.
As for how long it takes to work, you will likely start seeing results within a month. PM me if you want to know more. It's a great benefit IMHO. Good luck.