The WS so far as I know is roped off where it is closed (China through France?). If it's roped off, you can't do most of it, but you could still do it in Norway, Mexico, UK, Canada. That said, it's meant to be done on one walk around the WS, and you only spend maybe 2 minutes or less per country with no reason to enter the country. Not worth it to do half of the countries at a different time unless you're already walking by them.