meh, I dunno. My last time to the track I put on new pads/rotors the day before without a chance to go in a parking lot or anything. My strategy was to take it easy on the practice sessions. Well third or fourth lap in got a little heat in them and ended up jumping into a 18" deep puddle of 40* water. Probably not the best thing for them. They were fine though.
I know that part of it is you want to gas of the vapors from manufacturing that may be in the pad compound.
Hawk’s instruction said something about transferring the pad compound to the rotor. I am not really sure about the theory behind this, since it is always under friction aren’t you wearing off that layer all the time. Perhaps it promotes pad wear over rotor wear.
Of course getting all the molecules heated up and happy in their new home is going to give it a longer life, just as with heat cycling tires.