I recommend letting them marinate for at least 1 hour. At the restaurant we dust the ribs up to a day in advance. Place ribs on grill and cook for 1 1/2 to 2 hours. About 10 minutes before you remove the ribs from the grill, mop them with sauce.When you take them off the grill, mop again with sauce and sprinkle some more Magic Dust on them. recommend letting them marinate for at least 1 hour. At the restaurant we dust the ribs up to a day in advance. Place ribs on grill and cook for 1 1/2 to 2 hours. About 10 minutes before you remove the ribs from the grill, mop them with sauce.