1. Soak the bread slices in the milk for 10 minutes. Then remove the bread, squeeze it dry, and shred it. Set it aside.
2. In a large mixing bowl, combine the turkey, shredded bread, onion, eggs, thyme, and salt and pepper. Toss well. Then transfer the mixture to a food processor, and using the pulse action, process until it is well blended but not completely pureed. Cover, and refrigerate for 1 hour.
3. Combine the bread crumbs, parsley, paprika, and melted butter in a 9-inch pie plate. Stir with a fork.
4. Shape the chilled turkey mixture into six large patties. Coat them with the bread crumb mixture, cover with plastic wrap, and return to the refrigerator for 1 hour more.
5. Heat ½ cup of the corn oil and 1 tablespoon of the butter in a large skillet. Cook the croquettes over medium heat, three at a time, until golden: 7 minutes on one side and 5 minutes on the other. Set them aside and keep warm. Repeat with the remaining croquettes, adding more oil and butter as necessary.
6. Heat the turkey gravy, and serve the hot croquettes topped with gravy.