From what I've read (and my own experience, as this is my second time around) MS usually comes around 8/9 weeks. I'm 9 weeks along and I've had bouts of it off and on. Had it really bad around week 5 and now again in week 8 and 9.
mine started last week, but is only off and on..some days bad, others are alright. i'm just over 8 weeks now. with my girls i had it bad from about 8 weeks on...so i keep waiting for the shoe to drop...haha