FlyerTalk Evangelist and Ambassador: The British Airways Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Diam, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 33,190
Another way of phrasing Ditto's answer is that there is absolutely zero difference between changing your ticket on the day or x weeks or months before. Expect no added flexibility whatsoever due to it being 'same day', for AF (and most non-US airlines) it is an entirely irrelevant element.