I will say that while I doubt the line was put in with MEA in mind - Bioware hasn't shown that level of foresight previously so i'm not inclined to attribute it to them now - post Thessia is the point that makes the most sense to me for the ARK project to launch.
This is the point where the galaxy as a whole is out of the 'chicken with it's head cut off phase' of the Reaper invasion, and, to an extent, has it's act together, but at the same time, this is the darkest hour, morale's the lowest, it looks like the Reapers are going to win and our Hail Mary, the Crucible, is going to be a bust.
This is the point that, in my mind, the contingencies and back up plans get put into motion. This is where we start bunkering down, this is where we get out of Dodge.
The upside to this time scale is that we don't have to worry about the outcome of the endings and whether or not everyone has glowing matrix code on their skin and the true implications of that if they do.
The downside is that they would have to tackle, at the very least, the genophage cure, and whether or not the geth or quarians or neither were wiped out.
Personally I think those are issues they *should* tackle, but not everyone agrees.