Seems strange, but doing the knee strikes is an excellent way to learn how to pivot your standing foot when kicking. Please note that pivoting may not be as apparent or even necessary for low line kicks, but it will be absolutely crucial for mid to high level kicks, in order to do them safely and in good balance.
Practice these knee striking drills that will teach you how to pivot your standing foot daily. I would suggest to do these as a warm up after stretching. If you do 15-30min stretching before each lesson and 5-10min of pivot knee striking drills, by the time we get to mid level kicks you will be well prepared.