User blog comment:Trandra/N7 Day 2016/@comment-4953843-20161103174931/@comment-9753034-20161104111228

It's possible that the Council did in fact realise the bigger threat when Sovereign attacked the Citadel, and that work on the Andromeda Initiative began immediately after. Would be pretty sick if the Council's seeming dismissal and passiveness was be part of a scheme to keep the initiative secret from anyone who didn't have to know, including top operatives like Spectres.

I suppose it's also possible that the project started even before the events of ME1 -- sending people to Andromeda just for the hell of it -- but presumably there wouldn't be same need for secrecy, so it would seem very odd from the perspective of the trilogy that the Ark thing as good as never happened.