To be fair to DC, it rarely happened since the launch of the new 52.
DKIII which we knew would be delayed, Few Justice league delays towards the end, a secret six issue was delayed, and Hitches JLA.
I can totally emphathisize with your frustration, but they were pretty good at keeping their comics on schedule.
I'm just glad I stopped buying JLA after the first couple issues and waited for the trade as I have difficulty remembering month to month, never mind across delays. And I completely lose interest.
I'll grab this if it gets finished and released in a single volume.