I felt flutters for the first time at 17 weeks, maybe once a day until 20weeks where I felt kicks. Everyone is different, it all depends on how baby is lying, position of placenta etc etc. I'd just enjoy the sensation and not worry about frequency
Early on, it could be a couple days in between feeling any movements. For me, I felt the first flutters around 18 weeks. By 20 weeks, I was feeling at least small movements pretty much daily, sometimes several times, but it's different for everyone. Don't worry about frequency until about your third trimester.
Re: first time flutters