I prefer to start clamping while limp. I can position the clamp comfortably while I begin to swell. It also allows me to get the clamp as close to the pelvic bone as possible. It will get hard by itself, but I like the use of my partner. Once it gets swollen, a bulb forms at the base of your penis, at that point if you force the clamp to the pelvic bone, the bulb will slam it against the pelvic bone and you are set, it is almost hidden in the fat pad. I weigh 148 so I have hardly no fat pad, but I can feel that clamp pushing up againt my pelvic bone. The penis is as hard as a steel pipe. I have always said that when it get that hard, care has to be taken, because I believe a penis can possibly break in half.