When you are able to take Iodine in therapeutic dosage it shouldnt take long before the energy is back.
In my case the detox took 2-3 months; lots of flu, infections, diarrhea, pains etc. Energy came noticeably when I went over 50 mg of Iodine daily.
Difficult to say but in the cases I have worked with the energy is back within 1-4 months, depending on dosage and how severe the situation is.