If you are going to clone to find out sex, you can "top" them above the 3rd set of true leaves. Now, doing so you'll have about a good 4-5" that will be the clone. If it turns out male then kill it if you want. If female, you just got a 2 for 1 deal. By topping it, I feel they are more symmetrical than topping. Then you can train the 2 tops opposite of each other to spread them out. Hope this helps.