Easy one :
When Effective Military Strenght is measured by the game to trigger what will be delivered to the earth final fight ?
I have read the war asset thread which says at "priority : cerberus HQ" launch, and wikia which says at "priority: earth" launch
After finishing Chronos, look at your map. The ems that you have at that time is what you go to Earth with whatever that number is. Depending on what heppens to Anderson on the Citadel when facing TIM, that number can be higher or lower.
Based on Mikefest's experience with whether TIM kills Anderson or not, EMS is judged at the time of the decision. (Anderson is apparently worth 100 points if TIM does not kill him.)
If Shepard "saves" Anderson, Shepard will gain 200 war assets and if TIM kills Anderson, Shepard loses 100 war assets.
The 2 numbers above is not effected by your Galactic readiness. So if your Galactic readiness is at 50% you still get the full 200 and lose the full 100