I felt something reasonably definite at 16.5 weeks, but haven't felt anything quite so definite since. Guess it was bubba doing a 360 or something. They have become more regular at about 18 weeks (now) which is great and so reassuring. More like tapping sensation now, rather then the gassy/ripples that I felt before other then the 360. Bubba must be going to be an acrobat.