In medium saucepan over medium heat, combine chicken, vegetables, gravy, soup and thyme; bring to a boil, stirring occasionally.
Meanwhile, in medium bowl, combine baking mix and potatoes. Add warmed milk; stir with a fork until just combined. Let stand 2 minutes.
Transfer chicken mixture to a 9x9-inch baking dish that has been sprayed with cooking spray. Drop dough by 12 spoonfuls onto chicken mixture.
Bake in a preheated 400°F oven 30 minutes or until dumplings are cooked through and lightly browned.