Not all stories are based on the Gregorian Calendar. Writing fantasy / science-fiction with Storybook is awkward for numerous reasons and one of the glaringly obvious ones, to me, is time. I don’t expect you to implement a way for authors to invent their own calendars (though that would be really neat!), so perhaps a way to specify the chronology simply in terms of days (e.g. Day 1, Day 2, Day 3, etc)?