Ok, the Germans deploy jets in 1941. The US and British respond by pushing up their own jet development. As the US had already produced a six million square foot plant to build jet engines they didn't have yet (yes, GE did this in 1941) the facilities exist to manufacture huge numbers of jets in the US.
What would certainly happen is that the US and British would muddle along for much of 1942 and then simply swamp the Germans with equal or better jet fighters and bombers in huge numbers by 1943.
Technology is at best a very short term advantage of only small difference in war. The more important and dangerous a new technology is to an enemy the quicker and more effectively that technology will be countered. This is certain to be the case here.