Well dude, some of what PF says should be taken with a grain of salt. Then again, a lot of things he says are very true and important.In this case, if you are growing the PF strain you can wait for the primordia to appear which will decrease the time you have to wait on the first flush and could increase the yield from the first flush. With any other strain though you probably won't see primordia form in vitro.
I usually wait about 3 to 5 days after 100% colonization anyways to give the mycelium a chance to colonize the inside of the cake.