Forum:When does the EMS count?

EMS is known to have a great impact on the ending. However, it is not clear for me, that when is the point in the game, when it becomes insensible to changes (in eg. galactic readiness). I guess if it is in accordance with the narrative, the minute you attack on Earth EMS becomes Spear and Hammer, so further changes cannot be made. Or the actual state of readiness decides the ending when you are at the end of the game?

Technically, I am interested in that if I launch the final assault with a 5000+ EMS and during the mission I skip a few days, so the galactic readiness decreases is it possible that with it the EMS decreases also?