Herbed Chicken and Arugula Panini

Name: Herbed Chicken and Arugula Panini
Yield: 4 Servings
Ingredients: 1 pound thin chicken cutlets; 1 1/2 tablespoons chopped fresh thyme, divided; 6 tablespoons olive oil, divided; 2 garlic cloves, finely chopped; 3 tablespoons balsalmic vinegar; 8 1/3 to 1/2-inch thick slices olive bread or 4 crusty sandwich rolls; 1/2 red onion, thinly sliced; 1 bunch arugula