I've got a very interesting experiment going. Two weeks ago I made some cambozola using the recipe in Caldwell's book. That is the P. roqueforti is added to the mold when it is half full and then the rest of the curds are added. Four days later the cheese is pierced and a couple of days after this PC and Geo are sprayed onto the cheese surface. I got delayed by a couple of extra days after piercing but before spraying. By this time the blue had "tinted" the entire outside of the cheese. While too early to tell for sure it looks like the PC and Geo are going to overwhelm the P. roqueforti. I believe that this method is used because adding the PC and Geo to the cheese milk would inhibit the growth of the P. roqueforti.
I shall report back in a couple of days with a photo.