In case of an event sunday seems the best day to host them.
why?
Most people don't work on sunday.
Most people don't go to a party or wedding on a sunday, because they go to work or school the next day.
Most people have some free time on a sunday.
That said I also don't think the time schedule shouldn't be any later then 7/8 pm European time.
As for American/AUS/ASIAN players it will be quite hard to schedule at the same time as Europeans so they might be better off creating an event together.
But then again that's just my opinion.. but i also think the most reasonable one.