Unfortunately, this isn't possible. My list management service doesn't give me the option to determine when to send each person their daily lesson uniquely. Lessons are usually delivered at the same time of day as when you signed up. So for example, if you first subscribed to the lessons at 5:32pm Pacific, then your lessons will arrive each day around that time.
If it is important to you to start each lesson at the beginning of your day, one possibility is to set a calendar reminder notice that has a link to http://www.the-course-in-miracles.com/acim-forum where all of the lessons are posted. You can also try re-subscribing (with a different email address) at the time of day you wish to receive the lessons.