Most international stock markets follow the leads of Wall Street. If Wall Street clearly rallied or plunged today, then you could buy/sell foreign ETFs, after US markets closed?
does that game still work? that was the "follow the book trade across the globe" in the 1980's and 1990's
If you will watch ETFs representing foreign markets/indexes, then you'll see that they trade during the day somewhat in anticipation of following our market if there's been a big move.