I believe the answer you're looking for is that it takes about 24 hours for the T3 to effect your RMR. So you should be benefiting from it on the 2nd day. You may not notice any visual improvements for a week or so, but rest assured your metabolism will be faster after 24 hours. I've never gone above 50mcgs myself but even at that dose it really makes me lose the water and drops my weight even if I cheat a bit on my diet. I usually gain a good 5 pounds of water after my free day, but while on T3 at a measly 50mcgs I would sometimes end up lighter the day after my refeed. I can only imagine what 75-100 could accomplish.