What should I expect when starting a testosterone program? What is the time for testosterone to work and show effects? There is no precise answer. Every patient is different, their metabolism are different, their Total Testosterone and Free Testosterone levels are different, their baselines are different, their symptoms are different and their variables and influences are different. Testosterone replacement therapy is not a magic pill that changes your life overnight so make sure to temper and calibrate your expectations through education to avoid disappointment. Researchers have assessed TRT studies to understand how long it takes for the testosterone therapy to reach different symptoms of Low T.