Mid-cycle:
At the beginning of a cycle, kegg places a fertile window prediction based on your personal cycle data.  Occasionally users might see their fertile window move mid-cycle. When this happens kegg is analyzing the most recent readings and recognizing a potentially later fertile window.
At the completion of the cycle:
At the completion of the cycle, kegg will assess the full set of readings and place a fertile window confirmation. Well-timed and consistent daily kegg readings will help to provide the most accurate fertile window placement both during and after the cycle is completed.