Hi.. Our moms are at least 24" tall and have lots of flower tops to take cuttings from. We FIM the plants when they are younger so we get more flower tops to take the clones from. Good Luck!
Just make sure hat the plant won't suffer because of the missng limb. If you don't think it will go for it. If your really taking a vital part of its growth then wait til it grows.
Hi... Check out the stickie in the Advanced/Plant Training section which deals with FIMing and topping plants. It's a great way to get more flower tops.. really important when your taking clones. Here's the link http://forum.grasscity.com/plant-training/122559-how-fimming-topping-made-easy.html Good Luck!