" I read that this in a lot lower dosages helped your son get rid of his Body Odor ? (including a scalp odor) and really what my question is, is how long exactly did it take for you to notice a difference in the odor?"

-yes my eldest son had Body Odor from he was 10-11 years old.
Feet and scalp in particular. His shoes could sometimes smell like cat piss.
Not funny when the teens approached. He started Iodine at the age of 12. Within a year the Body Odor was gone, I cant be more exact as it went away so slowly and one day it was simply gone.

What I would add is zinc, vit B in addition to magnesium, vit c and selenium. This is what my son has been taking all these years.
Also plenty of salt, as Iodine may push out some bromide (that is smelly, especially armpits) -the chloride in the salt push this out.
Zinc is soo important for young males, and has a say in body odor. 30-50 mg balanced with a little copper. Cant remember the ratio right now.
Natural vit E works with zinc and selenium, taking them together will optimalize their effect.

I would also add some chlorella for a few months. 10-20 grams if you can afford it. It is a known odor killer.
Also other chlorofyll rich food or powders can be used, but chlorella works best in my experience.

Last but not least, a little boron, or borax. It is a known deodorizer for clothes and the house. Taken internally it affects the magnesium-calcium balance, important for hormones too! Read alot:)
-it may be a fungus aspect in your condition. So instead of expensive shampoos, try a borax cure; water,borax, Iodine and a few drops of essential oils like rosemary. massage into scalp, let it sit for half an hour or even over night. Then wash it out with a good shampoo. With good I mean as little chemicals as possible; they can be hormone disruptive. I like Audrey organics myself.

Imo,

All he needs is 50% water mixed with Lugols 5% and applied directly to the scalp, then Towel dry. I suffered for DECADES with severe dandruff. NOTHING worked. Expensive shampoos, Dandruff Shampoos, etc. etc.

The dandruff VANISHED on contact! This treatment lasted about 8 weeks before I needed to repeat it. Stubborn spots on the scalp may need to be treated for 2 or 3 days.

My Dandruff was never stinking, but I still think this procedure is well worth trying, especially since it might give him immediate results like it did for me.

IMO, he should also take the Iodine protocol for optimal health.

Grizz