If you ask a question of 10 brewers, you'll get 12 answers...
I really don't understand the instruction not to wait for fermentation to finish. You'll be moving the beer off the bulk of the yeast, before it's finished its job. If you really want to secondary, wait until you reach FG. Otherwise, you'll be starting a thread titled "Why is my FG so high?"
But then, I never secondary, so take it with a grain of salt.
"Anything worth doing, is worth doing slowly." ~~ Mae West