You can schedule messages and posts ahead of their posting time! This allows you to plan out a full week (or months) of content.
You can access the Scheduler anytime you make a post or message (whether in Mass Messages, on your wall, or from your vault). Just click the "Schedule" icon and choose the day and time for it be posted. Remember that posts can't be scheduled for the past.
You can also schedule messages and posts directly in the Scheduler page. On that page, you'll be able to see each day's scheduled post(s)/message(s) and directly edit it, reschedule, or delete them.