I think the best bet for a ceasefire would be in 1940 after the Fall of France, or 1944 after a victorious Battle of the Bulge.
Lets say that the Germans manage to wipe out the Bastogne pocket in December, and make a massive push to Antwerp by the end of the month, or Early January, surrounding Monty from the rest of the Allies. With over 1/3 of the WAllies in Europe threatened at being completely wiped out, the Western Allies sue for peace.
Germany receives the Netherlands, Luxembourg, Belgium, and Alsace-Lorraine. The treaty is signed in late January as the Soviets start towards Central Poland. Over 1 Million German soldiers begin to be transferred to the Eastern Front, bogging down the Soviets in Poland, but not making much ground. With W. Allied bombing stopped, the German industry has a chance to recover greatly, rebuilding many tanks and planes, keep the Soviets out of Germany, and slowly pushing them back to Russia, by May, the front lines are that of the start of Barbarossa, both sides absolutely exhausted, the Soviet morale now dead, loosing all of their allies. German morale is at a high with the peace in the West and Soviets slowly retreating. The war will continue to be a stalemate, taking place in Belorussia and East Prussia for most of the time.
By late 1945, the Soviets, embittered in battle with the Germans, sue for a ceasefire. The borders are now similar to that of Brest-Litovsk in 1918, and the war in Europe is over.