Germany were well advised to develop the Me262 and ill advised not to throw everything they could do to get them into service earlier. The He162 was a remarkable design but was
a) not what germany needed
b) another diversion of resources as was the Me163, Ta152, Do 335, and other late developments.
The 262 was almost immune to fighters with precious few shot down when in the air (apart from landing and take off) and lethal against bombers offering a one pass one kill capability. The He 162 with 2 x 20mm lacked this and the piston engined types didn't have the performance to stay out of the way of the Allied fighters.
In the first few months of WW2 the British realised that survival was the name of the game and forbade almost all development and concentrated on the production of a handful of aircraft.
Germany did of course concentrate on the production of fighters but didn't stop wasting resources on the development of aircraft that never had a serious chance of reaching combat and would have only had a marginal impact had they made the front line. Those designers, engineers, research facilities and scarce materials could well have impacted the in service date of the Me262, even 6 months would have made a huge difference.
I disagree.
The He 162 was
exactly what Germany needed and more so than the Me 262.
The He 162 was equipped with 2x MK108, which in my opinion iis enough to kill a B-24 or B-17 in a single pass. They only had to switch back to the MG151/20 for the He 162
A-2, which admittedly seems to be the only version used in any numbers by the JG1. The reason for the switch back to the MG151 was, according to the only source I have that bothers to give an explanation, that the MK108 "could no longer be delivered". Remember that this was in february to march 1945, so to me that seems plausible.
And no, an introduction of the Me 262 six months earlier than historically would not have a real impact on the situation over Germany in my opinion. I would say for any significant change the Me 262 would need to be available
in numbers around the same time the US started massive long range raids with escorts into Germany. That is late 1943, so around the same time the Ekdo 262 started its first hesitant flights with prototype Me 262s. So you would need at least 10 or so months for preparations, training familiarization with a completely new type of aircraft, ironing out the bugs and production of a larger number of birds.
So, in my opinion, only had the final production Me 262 A-1a been available in the early spring of 1943, it might've had significant impact.
Oh and the Me 163 was developed alongside the Me 262, it is
not a late-war, desperate development and to count it as such is unfair (imo). The V4 made it's maiden glide (engine was not ready) in the autumn of 1940. By the time the late war development rush kicked in it was already a mature design (if you can call a rocket plane mature) an proven to be more or less a failure in its given configuration.