Could you clarify what you mean by the second leafing stage? The plant is getting its second set of leaves?

Remember, no nutes for the first 2 weeks. After that, its ok to feed it about 1/2 or 1/4 the recommended manufacturer dose of veg nutrients. In the vegetative stage you want a higher nitrogen to phosphorus ratio, I use FoxFarm's Grow Big which is 12-7-7. Then about a week or 2 after you switch to flowering you change to nutrients that are higher in phosphorus and lower in nitrogen, like the FoxFarm Tiger Bloom I will be using (2-8-4). Just remember, its really easy to over-feed a plant, which is harder to correct than not enough nutes. Start off slow and work your way up. Here's a link with a little more info, and look through the grow faqs. Also, the second link is to a site that helps diagnose plant problems, like specifically what element your plant is lacking or has too much of.

http://www.a1b2c3.com/drugs/mjgrow9e.htm
http://www.drugs-forum.com/growfaq/97.htm

Also, if you only started one plant, you might want to start another to increase your chances of getting a female, cause it would blow to put all that effort in and come out with only a male.