Zero days, felt better after the first dose of 50 mg. I upped to 50 twice a day and felt better, then got brave and upped to 200 mg a day and was astounded. I may up it again in a few weeks just to see what happens.
I started taking it for hypothyroidism, and my energy went through the roof and brain fog cleared up. My vision got sharper and I could see amazing colors and patterns in everything - kinda hard to explain but my vision is better than I can ever remember it being (I wear contacts).
I got kinda "punchy" meaning I gave a damn about things again and was motivated to start running again and work on personal improvement. This, for sure, was the flouride coming out. Flouride is a depressant and a demotivator.
This is probably the most awesome, most beneficial supplement I have ever experienced. I'm referring to Lugol's 5% (10% potassium iodide, 5% iodine), approx. 6.25mg/vertical drop.