First pregnancy for me, I felt several weird butterfly-like flutters in week 14, but it was only a couple and pretty early so I convinced myself it wasn't baby. I didn't feel anything else until week 16, when I started feeling what I thought were muscle twitches. I waited a few days to make sure they kept up before accepting that they were baby. Now, in week 19, the baby was kicking so hard that the other night, they actually kept me awake from 10:30 all the way until 1am.