You can start any time you like -- it's an individual/group thing, non-sanctioned and non - SAG supported. Start where and when you want to, and go either direction. Start with lights at 4AM, and be home in time for lunch!!!! Just be sure to be through Richardson/NDallas/Addison early in the morning!!! And I daresay, stop at all stop signs -- methinks the local gendarmes will be out in force, writing tickets.........
I'm probably doing the Tour de Norway 80-miler the day before, so probably won't be doing this....