If it's a sativa then the growth is normal. Most sativa's take a minimum of 10 - 12 weeks with some sativa's taking 14 - 20 weeks to be done. You still have probably 6 weeks maybe more. The light cycle is fine. I've used 10/14 on long flowering sativa's to get them to finish faster. Just keep doing what they're doing and don't let your friend rush you and harvest early. The flowers are not likely to develop into dense buds like an indica strain and you really need more light. Be patient, let them finish, and you should harvest some good smoke.
Good luck.