Will I pass a drug test 8 days after smoking????????

Maybe, maybe not. You can test positive up to a month after prolonged daily use, but it's more like a week for using once or twice, so you're right on the borderline. There's no evidence that cleanses or B-100 pills work, and the later could be toxic if you take them long enough. Just get enough sleep, eat healthy, drink enough water (but not absurd amounts), and you'll probably be fine. But really, assuming you're still in high school, you shouldn't be smoking weed anyway, because it increases your risk of later developing schizophrenia. The older you get, the less severe this effect is, and by the time you're in your 20s, it's gone, or effectively gone. So if you want to blaze, that's cool, but wait until your brain has developed a bit more, okay?