For the 650, the magic number is 6.
It takes six manual steps of the primer mechanism to get a primer in the proper place for the first case coming down the drop tube.
You will see a little metallic lever that is part of the ratchet system. Cycle it 6 times to set up the first primer. Then load cases in the drop tube (manually or with the case feeder).
"No matter how cynical you become, it's never enough to keep up." - Lily Tomlin