You should see sex identifier's by the 4th or 5th internode that's when they pre sex, you should have your lights on 24 hours at the first 8 weeks at least, and around 3 inches from the top of the plant if it's under a FLOURO , over all it looks good and healthy, keep your eyes peeled for purple stems, that ussually means under nourished with nitrogen. I should just shut up now. Good luck dude