MS clarified that they're allowing some places to start shipping before October 22, but that's so that things arrive by about October 22.
They're not really releasing things early or letting them go on sale early.
And they have to have a universal date for everyplace to start selling, and that gives everyplace time to get ready. If they don't have a universal date, everybody is going to rush to be the first ones out the door.
And it's the big OEM's -- the biggest contracts and source of funding -- who need the most time to get ready, get things pre-assembled, etc.