In addition to what fab five has said, they have also said that enough managers will be promoted to fill D.III to start the second season, then enough to fill D.II for third season and finally enough to fill D.I in the fourth season. This is all covered in the News posting.
As for how many active owners there will be at the start, how do you have any idea how many have signed up? You aren't taking this poll as having any value, are you?