I have cut off a couple of buds at 6 - 6 1/2 weeks and got a decent buzz, however, you are best to wait until 8 weeks when you harvest. The quality will be soooooo much better. Also think about how much bigger the bud you will smoke, would have gotten in those 2 weeks, it's kind of a waste, but don't let that stop you.

Best of luck

L0rdsOth