I had it at 11 weeks. There were signs of a problem with my baby at my NT scan and for various reasons, I elected to go with having a CVS right there instead of waiting for an amnio. Depending on where your placenta is, it can be done either transvaginally or transabdominally. My placenta was in the front, so mine was transabdominal - it was very similar to what I have seen amnios look like. I had a local anesthetic to numb my belly, then a large, long needle to collect the sample. It was uncomfortable but not painful. The perinatologist who did it does them every day and has a lot of experience. (I think that is crucial.)
Afterward, I rested that day and the next day and for about 3 or 4 days after, didn't lift anything heavy. (But I did have a 2 year old at the time, so I did care for him, just tried not to carry him.) I also had a big bruise and some tenderness at the insertion site for awhile.
They did a FISH probe which can come back in 2 days, although mine took 5. I got final results about 2 weeks later.
I was opposed to invasive testing (for myself) just because of my age (37 at the time), but because we were looking at a serious problem for the baby, I needed to know what we were up against. So, in that case, yes, I would definitely do it again.
Feel free to ask any more questions.