The best way to know if the chicken is done is to cut between the leg and the thigh. If the meat is no longer pink and the juices run clear, it's done. However, it's really important to let meat rest after it comes out of the oven. Cover the pan with aluminum foil and allow the chicken to rest for 15 minutes. The reason you don't want to overcook a chicken is because it will keep cooking under the foil and the juices will get back into the meat.