Testes completely descend into the scrotum by the age of:

Testes begin to descend from abdomen to scrotum between 28 to 30 weeks of gestation. By term, 95% of testes in infants are in the scrotum. Descent of testes from the abdomen into the scrotum is an androgen dependent process during which the testes are pulled downward by a fibrous cord anchored to the developing scrotum called gubernaculum.The testes sit just above the inguinal ring until the last 3 months of pregnancy, at which time they complete their descent through the inguinal canal into the scrotum.Testicular descent requires fetal gonadotropins. Disruption in the fetal hypothalamic testicular axis result in cryptorchidism.