Faculty choose when to publish courses at any time after initial course creation. Immediately after faculty publish the course, students will be able to access it, however they cannot submit assignments until several days before the start of the course. If the course is unpublished, it will still appear in Canvas under Courses > All Courses, but the course will not be accessible until published by the faculty.
This general schedule is not exact, but does describe our current approach to scheduling LMS data loads.