Pre-heating Charcoal Grill

How long does charcoal have to pre-heat? What happens if you do not heat it long enough?

With an igniting fireplace, it takes about 15 to 20 minutes for the coal to be thoroughly annealed. Fuels need a little longer. If charcoal or briquettes are covered with an ash layer, the fun of barbecuing can begin. Too short to heat up can lead to the fuel not burning completely and insufficiently releasing the required heat.