Look at a globe, and I think you ll get the picture. Santa simply sets off on Christmas Eve and travels in every direction at once, simply by heading south. Trust me, it makes a big difference. Secondly, and most importantly, are the time zones. Get your globe back out and have a look at those lines that run north and south.
All meridians meet and form a point at the poles.
That is to say the North Pole is in every time zone at once. Not only that, it s also in none of them. Santa Claus can leave home at noon on the 26th and still be out of your house before you wipe the sleep from your eyes on Christmas morning. And take time off at every house to have a couple cookies. If he ever falls behind all he has to do is go home and then head south again.