11 weeks when I started to feel flutters. I thought I was NUTS! By 13 weeks I was feeling movement fairly often and by 16 weeks I could feel them daily. I didn't know I had twins until 20 weeks so I figured it was just because I was having my "fifth" baby.
Around 20 weeks for anything definite, and I had felt movement waaaay earlier in my previous preg - go figure!
exactly like me- I was so worried at first because I was just starting to really feel definate movement about 2 wks before my u/s. I felt my 2nd at 11wks and knew for sure by 13! My first by 15, and my 3rd about 18. The twins was the latest! LOL