User blog comment:Garhdo/How long was the Reaper War?/@comment-4508344-20130901054526

From the Alliance News Network we know the attack on Earth was somewhere between Sept 21st (when Batarian refugees start arriving) and 28th when Primarch Fedorian announces Taetrus has fallen to a similar Reaper fleet as that attacked Human and Batarian Space. Fedorian then said on Oct 5th the attempt to retake Taetrus had failed, and Reapers had entered the Palaven system. So the mission on Menae must be around the 6th October.

This shows the game time between missions is not really that fast - all Shepard did in the game between these missions was visit the Citadel council.

On flight times - even if Mass Relay transit is instantaneous, flying between systems is not - the distances are vast even between close stars. FTL speed is around 5,479x light speed for Citadel ships. That means to get to the very closest star to earth takes 6 hours - in every cluster there are thousands of stars, and only a few spread out have inhabited worlds - so the Normandy could easily spend a week exploring some of the bigger systems.

This of course assumes you do all the gaw/side missions - depends how completionist you want to be.

Hackett/Shep post rannoch do say weeks - but this doesn't necessary mean just 1-2 weeks. 12-18 weeks is "a few weeks" compared to 300yrs.

My head-cannon suggests Citadel Coup happens around new year (3 months to save the Krogan and do all the pre coup missions), then 3 months for Rannoch, Citadel, other DLC, Thessia about April 2187 and Earth not too long after that. So I agree 6-9 months.