How long should i marinate the chicken?

Name: Grilled chicken with white sauce
Prep time: 20 min
Cook time: 50 min
Total time: 70 min
Yield: 3
Cuisine: American
Ingredients: 1 whole Chicken breast (500 to 600 ) cut into fillets; 3 tbsp Olive oil; 1 tsp Garlic powder; 1 tsp onion powder; 1 tsp mixed herbs; 1 tsp paprika powder; 1 tsp black pepper; Salt to taste; For white sauce,; 3 tbsp all purpose flour; pinch of thyme; pinch of chicken powder; Salt and pepper to taste (for sauce); 0.5 cup Milk; 2 tbsp butter; Vegetables of your choice for sauteed vegetables; I used potato and carrots; Marinate the chicken fillets with the top six ingredients; Refrigerate for an hour at least; Grilled chicken on hot grilled pan; 5 minutes each side over medium to high flame; Put some butter the other pan; Prepare a roux by sautéing all-purpose flour melted butter until smooth and slightly fragrant; Add thyme, chicken powder, salt and pepper; Gradually add milk while stirring continuously; If sauce is thick than your desired consistency; add some hot water and stirr well; Cut vegetables into cubes or slice sauteed them little olive oil with salt and pepper; You may add any herb of your liking to vegetables; serve two chicken fillets poured with white sauce along with sauteed vegetables.