Timeline of the Battle of Installation 04
From Halopedia, the Halo wiki
This is a timeline of the events slightly before, during, and slightly after the Battle of Installation 04. The battle primarily lasted between September 19 and September 22, 2552, though notable skirmishes and engagements took place before and after this timeframe. Concurrently with these events, the final stages of the Fall of Reach were taking place.
August 2552 - the Fall of Reach
Several official timelines of the Battle of Installation 04 have been published by 343 Industries. They are linked below for convenience.