I had my first one about 3 weeks before my due date and I was going to do the same with my second but I ended up having to have Ann emergency c section 5 weeks early so I did it afterwards
I had one at 19 weeks because we had to fly for a few hours to get there, and I plan on having one where I live at about 32 weeks. it felt a LITTLE early at 19 weeks, cause I was only showing a little bit. hopefully 32 weeks will be a good spot for me, so I'm not too tired, but I want to look really pregnant for photos lol.