yay for you on feeling flutters so early.
It's perfectly normal for you to only feel them occasionally, when your bubs has so much room to move.
The early on ones I felt were normally when i was bent over squishing bubs a bit, and I got little protests.
You will know once the kicking really starts, and don't forget that bubs does sleep for at least half an hour at a time, so if you don't feel movement, just relax, give it a chance to wake up and then once your about to drift off to sleep yourself, it will start dancing.