what would be more relevant is the load on your flight. If oversold and there is a risk of denied boarding and paying compensation they may look to mitigate that risk by moving passengers to an earlier flight assuming availability. If your flight is not chockers it is very unlikely...unless, as you say, christmas spirit is in the air
I have asked previously (Avios domestic booking...had planned to have escort one passenger from LCY to Waterloo and head back so accounted for that in the timings but plans changed so was able to remain at City...was met with a resounding 'no')