Not really, I think 15 is a good age to get into cologne, although just don't be like every typical teenager and douse yourself with the stuff. 2 or 3 sprays is usually more than enough for you and those in your close vicinity to enjoy.
As for A*Men and London, I love London. Not so keen on A*Men, too strong and obnoxious for me. They both say colder weather though, so maybe not so appropriate for another month or two.