Watopia is available every day while the other worlds rotate as the “Guest World” according to the calendar below. This gives Zwifters access to two worlds (Watopia + Guest) at any given time.
8 Richmond days in February. What do you suppose Zwift has up their sleeve?
Keep in mind the guest course changeover happens at 20:00 Los Angeles time (PST) or UTC-8 hrs.
If you’d like to ride an off-schedule course, see How to ride any Zwift course at any time using the <world> tag. Events may also be held on off-schedule courses.