As someone who remembers going into his teenage years, noticing girls, and thinking about his appearance when the school year rolled in, 12 or 13 years of age (around middle school age) is when you could start wearing cologne. Albeit, you want to start with lighter fragrances like Curve for Men by Liz Claiborne. With that said, starting with cologne at an early age, you might want to verify with not only your parents but also check with your school's dress code.