If you took prenatal yoga classes, around which week did you start? Or how far along were the other women in the class?

I'm 9 weeks and did some yoga just before I got pregnant. In previous pregnancies I was told absolutely no exercise before 12 weeks but I think they've eased up for this one, although I am still high-risk just not for anything that could be exacerbated by yoga. I thought I'd wait it out till 2nd tri but as soon as 9 weeks hit I've been itching to do something! Would it look ridiculous to do a prenatal class when I'm not showing yet?