That plant is about 14 inches tall at the moment. I think that most plants will show their sex when they have fully matured and you don't have to switch to 12/12 for "preflowers" to show up.

This lights I'm using are called fluorex made by lights of america, they are 65w each and produce 4550 lumens. You have to get them within an inch of the tops of the plants to get the most out of these lights and minimize the area you are giving light to.You also need a fan blowing across the tops of the plants cause they do get pretty hot. I had 3 of these in about 2.5 square feet of space which gradually increased as the plants got taller. The lights are good for seedling and part of veg but they are not as good as a mh for veg. The lights are good but I would still add some of those coilshaped fluro's that fit in a regular socket for side lighting.

Here's a link to ebay where you can get them pretty cheap
http://cgi.ebay.com/6-FLUOREX-FLUORE...QQcmdZViewItem

the lights have to be wired to a powercord up before you can use them. results may vary