Discussion topic for all the GMs that are running Dungeon World:
How often do you advance the grim portents of your fronts? The are no concrete rules about it, so it makes me wonder about how everyone handles that part of the game.
In my case, I give my players two or three sessions of not interacting with a front before I advance it, and make that advancement clear and evident. I like this because it gives my players both the sensation of effecting the world and being just behind the bad guys and trying to catch up.