The last thing I heard was 60 days after launch. No I am not a Dev or anyone with authority, just stating what I, as a new person (only been here for last couple of weeks), have heard on the topic. An official answer for this would be great!
I think it just works on the coinage. If it was to work on corpse and chest loots too I would think they might have called it a Loot Gain instead of Gold Gain. This of course is just my speculation.