Managing scheduled Banner sets
To manage how banner sets should be scheduled isn't harder than moving the banner sets around in the calendar. To adjust the time frame for a banner set, simply click and drag the end of the banner set you wish to adjust. If you need to specify a more specific date/time, start by clicking on the the banner set and then click on Settings. From there you can specify the date and specific time (down to quarters of an hour).
From the settings you're able to specify more specific time frames, activate and pause the scheduled banner set and also weigh multiple banner sets that are running simultaneously against each other. For example, if you set the weigh of Banner set 1 to 1 and Banner set 2 to 2 then Banner set 2 will potentially be displayed twice as much as Banner set 1. The Override setting simply overrides any other banner sets that are running simultaneously in the schedule.
Backup banner set
What is generally recommended is to setup a backup banner set (under the Schedule settings) which will act as a backup when none of the scheduled banner sets can fill a given placeholder at any point in time. The backup banner set is usually ought to be a banner set that is designated to just be a backup so in general terms have a more generic banner design and have all formats and languages that you use throughout your banner sets, solely so that everything is backed up. Note however that this is completely optional and that if a placeholder can't be filled by either the active banner set nor the backup then the placeholder will render nothing.
Previewing the schedule
The schedule can be previewed at any time by either clicking on the preview button for each respective placeholder in the list of placeholders or by clicking on Preview just above the banner set in the calendar.
From the preview popover that appears, you can spoof the current time to preview the placeholder based on the time/date you select which is handy when you want to know how the schedule plays out.
To publish schedules, begin by saving the schedule. Once saved, the Publish button will appear instead, click it and publish exactly the same way as you would publish regular banners.