This thing is moving like I can't believe. I didn't feel Naomi until she was 22 weeks along. She didn't quicken until 24 weeks. We didn't see her tumbling in the womb (from the outside) until after 7 months. Even then she only had a few active times a day. This one is going on and on. I love it!
They say that if you are thin then you will feel the movements a little earlier. I was the same size as when I got pregnant with Naomi, but I haven't gained as much weight (about 10+ pounds less with this one) in the first trimester so maybe that's why I can feel it earlier. Plus I'm experienced now and know what to look for. However, that doesn't account for the belly jumping an inch every second.