1 discussion a week seems to be working so far. It helps create a sense of urgency in getting people to read the story and discuss it in a timely manner (I find people are reluctant to join a conversation if it seems too much time has passed since the last comment was posted). It is also good in case readers aren't interested in the story of the week--they can just wait a week for the next.
I second kate_the_reader's suggestions of reminders about the stories coming up. I find lots of reminders useful in notifying participants in pretty much all situations. Include a reminder list of what fics are coming up in the discussion posts themselves (just tack it on at the end, 'Fic discussions coming up: x by Y, a by C, etc' You can also post reminders of the upcoming schedules to the tumblr, LJ, etc throughout the month aside from the fic discussion posts.
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Date: 2016-03-17 08:32 pm (UTC)I second