When do i know that my plant is cloneable?
In theory, a plant can be cloned at any time during its life cycle past the seedling stage, though rapid vegetative growth phase is the time when you're going to have the highest likelihood of success.
I think the answer is that technically any cutting that has mature fan leaves on it could potentially root. So you wouldn't even necessarily need three nodes. . .as long as you're willing to kill the mother by taking the clone!
In practice, I'd say you probably want to wait until the plant has at least 5 nodes on it, and is at least a month old.
You don't need to wait until the plant is sexually mature before cloning it, but in practice, you probably will want to know the gender prior to bothering with the clones.