For all the fathers on here debating on when or whether or not to share this information, i myself included. First and mostly is you have to make sure your child is mentally mature to handle such information. Many kids from 12 up to even 18 are not ready mentally. THe second thing and this is just as important as the young boys maturity level is the approach that you, the adult, take in initiating the conversation and what comes after such as questions the little one may have.
I believe my son is close to ready for our PE talk but I am holding off for a little bit. This may be the right move but will never know. My son is very mature for his age, from what I see of him but as we all know that could be a front. Anyways, as I prepare for our discussion I will play out a variety of scenarios in my head to get a jist of what may come, that way I am some what prepared. I will think of all the questions that I would've asked given it was me in his position and I will think of a variety of educated answers. It will all be about penis health as opposed to penis enlargement. Communication needs to be important IMO. After all you want to know if your son has injured himself with the light stretches you let him on and so forth. To me, this is when pointers can be given out. Im babbling now so Im going to get off. I Can't wait to read some of the other replies.