When does the Krebs Cycle occur?

The Krebs cycle occurs when two carbon fragments that are produced by the removal of carbon atoms from the pyruvic acid, enters a series of reactions. The reactions are what's known as the Krebs Cycle.

Before the Krebs Cycle occurs, each pyruvic acid molecule breaks down into a two piece, or fragment molecule, and a carbon dioxide molecule.

Now here is where in my humble opinion the Krebs cycle occurs. If an ATP is a necessity, (energy) the two - carbon fragments ENTER the Krebs cycle. It then joins with a four carbon sugar. More reactions occur, carbon dioxide is produced along with ATP (energy), and it regenerates the starting material.