I seem to remember somewhere there is a consensus that Vito was shot on or about December 21. That would mean that at the earliest, Michael would have gone to Kay to tell her to go home, and then go to the hospital and get hit by McCluskey on the 22nd. The following morning, the 23rd would have been when
Michael told everyone about his idea to kill Sollozzo and a meeting would have been arranged shortly thereafter. As I recall when the meeting was held there were no signs of Christmas decorations in Louis Restaurant indicating it was after New Years' or even Jan 6, the feast of the Epphany when catholics traditionally took their decorations down, that the meeting took place.
Does this mean there was a sort of ceasefire over the holiays?
And if so who cooked the Corleone's Christmas Dinner? Mamma or Clemenza?