According to HowStuffWorks, boys or young men can start shaving their faces once they have enough hair to shave. Boys typically start to grow facial hair between the ages of 9 and 15, but they may not need to shave for some time after that.
A boy must be able to handle a razor safely before he starts shaving. If he shaves after a bath or shower, he is more likely to avoid cutting himself. Using a sharp razor and shaving gel also helps him to learn the process safely. Shaving in the direction the hair grows is recommended. If shaving irritates the face, an electric razor may be a good option.