You may want to consider cloning your plants.. being that you are starting from seed with the first one.. these would be perfect to start a new line of clones. Its not terribly difficult to do.. there are a few vids on youtube showing various techniques... but this is a great way to guarantee female plants with every crop. Just before you flip your plants to 12/12, take 4 or 5 clones off of each plant, and keep them seperated and labled so you can keep track of which clones came from which plant. Then.. when your plants start to show thier sex, you can scrap any male clones and keep the females for mother plants. Keeping 3 or 4 mother plants will easily allow you to take 50-60 cuttings every 2 months as needed.. just make sure you take cuttings off your mothers 2 weeks before your crop is set to come down.. that way your babies will be rooted and ready to transplant on time! Its a great way to perpetuate your crop without having the hassle of buying seeds and sexing the plants all the time.. All it takes is about 40 bucks worth of supplies from home depot.. and you can get your own little cloning set up happening.. Cheers!