I expect he'll get maybe 10-20 snaps on Sunday. If he does well, he'll get more the following week, and so on.
No way he just becomes a starter immediately IMO, sends a terrible message to the rest of the players when the D has been doing well.
But if he goes out there and makes more of his snaps than Trevathan and Brooking do then nobody on the team will complain if he ends up being a starter in a few weeks. He's more talented than either of those two for sure, but he has to earn his spot in the lineup.