With a POD after September 1, 1914, have WW1 end on or before December 25th of the same year. Is this possible?
Possibly with a few good PODs and some luck. Say the Irish question pops off just before WW1 and distracts the UK, keeping them out. One of those unlikely things that is a wrench in the works, the exact wrong thing at the wrong time for the Entente. Maybe India gets a case of rebellion or something else happens. Mix and match multiple such things as needed.
For whatever reason - bribery, a different political calculus, whatever - the Italians honor their commitments and join the Central Powers in '14. They don't have to do that much, but another front and headache puts more pressure on France and increases the perception that France is in over their heads. Additionally, a few of the independent neutrals decide to hop into the Central Powers early as a result of the zeitgeist seeming to doom France,. Purely opportunistic sort of things, people looking to get slices out of the Entente.
Toss in that the Eastern Front goes better overall in '14. Nothing gigantic here, just enough to make the Central Powers look stronger here and Russia weaker. It probably don't need to be a lot.
With no UK and a few more breaks, the Germans do better in the West. Maybe they take Paris, maybe they don't. Let's say they do for the moment. France is further against the wall and things look ugly for them. Russia's not making much progress on the Eastern Front, the UK had to bow out due to internal strife and lots of secondary powers are trying to get a piece of the pie. With everything going wrong in this war and no sign of immediate relief from the Russians, naked pragmatism takes the day and France manages to wrangle a decent peace deal. It's the legendary short war in the West, the dream of every German general before 1914. With France out, Russia faces political realities and decides to make a deal, wrangle a few concessions about Serbia in exchange for border adjustments, a bit of money and the political capital to say they stood up for the Balkan Slavs.
In a way it feels like it's reproducing 1940 in 1914 for Germany, but sometimes countries get on a lucky streak. No one besides Austria-Hungary and maybe Germany likes it, but Serbia gets it on the chin and Christmas 1914 passes in peace. Future Christmases not so much since the underlying tensions haven't been addressed, but that'll probably stave it off for at least a few years, if not longer.