Swiss and Sweden were neutral in WW2 although the Swiss had some scruffles with the LW. Doesn't change much about the starting date.
Bear in mind, that on the 1st of September 1939, all of a sudden MILLIONS of troops are on the move (Well at least hundreds of thousands) as well as thousands of aircraft and people are falling by thousands every day. A very different reality than on the 31'st ofg August. 1939.
The first day or two in Poland would probably have brought more dead than Pearl harbour.....from the top of my head.
