It would be much easier to start with 6 seedlings 24/0 and flower them after 2 weeks. Ditch 3 of them, carefully transplant your females, and continue flowering. Better yet, put one female back in veg to clone for your next grow. When it comes to bagseed, always germ 2-3x what you expect to flower. I've had great results with this method.
Transplanting during flower can stress your plants, but if you're careful they'll be fine. Mine bounce back in 2-3 days.
Do you plan on upgrading your setup as you go? I use 400w of cfl from the top only, and anything taller than 12" starts to lose bottom leaves from lack of light. I think scrog setups are the most efficient use of light, too labor-intensive for me though