How soon depends on the quality of embalming, burial container, burial location (such as mausoleum or in-ground). One funeral director I know exhumed a body 5 years after it was buried.
Definition: Aerobic metabolism is the creation of energy through the combustion of carbohydrates and fats in the presence of oxygen. The only byproducts are carbon dioxide and water, which your body disposes of by breathing and sweating.
Aerobic respiration is the release of energy from glucose or another organic substrate in the presence of Oxygen. Strictly speaking aerobic means in air, but it is the Oxygen in the air which is necessary for aerobic respiration. Anaerobic respiration is in the absence of air.