The first day, Home Day, is your continent's day. After that, you simply move eastward from continent to continent. The seventh day is Antarctica Day, or World Day, because Antarctica is shared by all nations.
For a North American, World Week would look like this:
1. North America Day.
2. South America Day.
3. Africa Day.
4. Europe Day.
5. Asia Day.
6. Australia and Oceania Day.
7. Antarctica Day, or World Day.