Good heat control begins before the food reaches the grate. A charcoal grill needs time to settle, so light the fuel well before guests expect to eat. Wait until much of the charcoal is covered with a pale grey ash and the flames have reduced.
Black pieces with tall, uneven flames are still developing and can produce sharp bursts of heat.
The ash coating is not a guarantee of perfect temperature, but it usually signals a more even fire than freshly lit fuel. Rushing this stage often creates problems that are difficult to correct once food is cooking.