You can find the start date and course duration for each course on its course description page.
If you are registered for a course, you’ll also see its start date and time listed next to the course on your dashboard. A course may start at any time throughout the day on its start date. If you find your course is not immediately available, please check back later in the day. Course timing is flexible; you do not need to log in exactly when the course begins.
For other dates like the upgrade deadline or course end date, see the right side of the Home Tab within the course: