The group schedule sets calendar dates for opening lessons for everyone at once (or for a selected stream), rather than from the student's personal start date.
In the Schedule tab, select the Group schedule type and click Apply—you can still change the type. Then, enter lesson dates and times manually or through the lesson planner, which is available when working with classrooms. For streams, select the desired cohort in the filter, and for classrooms, you can specify the lesson location. Save the schedule.
When a student clicks "Start Learning," the start is usually tied to the date of the first lesson or stream—see How does the "Start Learning" button work?
To set up a group schedule, open the Courses section, select a course, and on its page, go to the Schedule tab, where you can select Group Schedule.