How long does it take for effects of testosterone replacement therapy for hypogonadism?

Usually after 3-4th. Cycle but full effect can only be expected if serum testosterone levels are checked and are in the mid to upper third centile.
Depends! Time for effects of testosterone replacement to be noticeable depend upon route/dose, effect & you! most branded t can make subjective improvements in mood, thinking, sex drive (libido) & erectile function in days if given in an adequate dose. But increase in muscle & loss of fat will only occur if you eat right & exercise in add'n to taking t. If you take too much t, conversion into e2 will rob u.