A gold star for fructis:
I think its because if you exercise rigorously then your blood goes to where its most needed
That said, regular cardio exercise is absolutely good for your erection quality. By this I mean if you have incorpoarated some sort of high intensity cardio as part of your daily routine. In as little as two weeks your body will improve your circulation and overall aerobic function. Your heart will begin to be stronger, and therefore your erections as well.
This goes hand in hand with eating well, not smoking, etc.
So the supposition is correct: good cardio health = equals better erections and blood flow, which can only be an aid to PE.
Should you do your aerobics immediately before PE?
Depends on what you mean by “immediately”. I would say that you would want to make sure that your body was somewhat recovered from the aerobics; having regained the resting heart rate for a bit, before launching oneself into a heavy PE routine.
So some time in between would seem warranted to me. An hour would be the minimum in my estimation.
Before: I'd like to show you something I'm very proud of, but you'll have to move real close.
After: I\'d like to show you something I\'m very proud of, but you guys in the front row will have to stand back.
God gave men both a penis and a brain, but unfortunately not enough blood supply to run both at the same time. - Robin Williams (: