Any steps you are going to take into cleansing your body should be baby steps or else you will get so much die off that you will feel real bad and you will want to give up.
The general idea thus is to go one step at a time. I generally start with 1/4 of the recommended dosage of ANY types of treatment I want to do and I see how my body adjusts. If my body still needs adjusting I will stick to this 1/4 until I feel ready to go to half the dosage and again give a chance for my body to adjust.
Furthermore, I wish it were simply a matter of potassium and magnesium, but it is far more complex than just that . Die off may be a need for antioxydants: Vitamin A C E etc. It can be due to a selenium deficiency or a magnesium deficiency or else a vitamin B complex deficiency. The specific die-off symptoms you get will let you know how to react.
Palpitation might also be telling you you need more fiber in your diet. The key word is to listen to your body, do baby steps and monitor how your body reacts.