You can start whenever you choose to. Many guys will start with advanced exercises or equipment, it really is all part of the same conditioning process no matter how you do it. I advise starting with basics and building from there but some men do not want to wait. If it were me I would not clamp at all, it is risky, causes discoloration, very easy to cause thrombosis...there are safer ways. But, if you do insist, check out the posts of Redzulu, he is the prophet of Clamping.