I take 1 drop of the iodine. But I have bad headaches. I really want to keep going and take the selenium now. Should I?

If you want to go faster than what I recommend, you are free to do so. But don't be surprised if you experience reactions and you feel worse at first. If that happens, you will need to drop back down to a lower dosage, stay there for a longer period of time, and then continue moving forward at a later date.