A reasonable time would have been better, rather than directly after the came out. Overkill can, and have, been cryptic in how certain achievements have been reached. You didn't even give enough time to actually try between release and post.
I have been on this site for about two years so far and so far I have not heard yet of a "gap time" between post-release and question asking. As far as I know, the rules have been: Don't ask questions about unreleased games and content.
I asked that question shortly after the update came out, asking it after I had actually played the heist.
Unfortunately I am unsure as of now what to do. Did I err here? Is there really this fabled "gap time" that MattR speaks of?