I think your idea of the development timescale is a bit overambitious.T. A. Gardner wrote: ↑17 Oct 2020 16:18
The US, not being stupid, would also push aircraft into production like the B-45 most likely by 1947 at the latest and more likely by late 1945. The B-45 was started as a design in late 1944 and in wartime I'd expect flying prototypes within 6 or so months. It used extant technology so it wasn't a ground breaking design. The rival B-47 and B-48 (Martin) were slower to develop and the B-47 involved considerably more cutting edge technology, so they'd be slower to get into service.
While everyone remembers the Mustang (prototype contracted April 1940 and flying on 25th Oct 1940), it was very much an exception. The first production aircraft didn't leave the production line until April 1941. Delivery to the UK took until Oct and squadron service entry was in Feb 1942. So ignoring the 6 month shipping delay, 16 months from start of design to front line.
One of the quickest wartime aircraft development projects was the Grumman F8F Bearcat. Development began in July 1943 and was completed in November with orders for the prototype placed that month. It flew in Aug 1944. Production was ordered in Oct and the first production aircraft rolled out of the experimental ship in Dec 1944 and deliveries to the USN began in Feb 1945 and the first squadron formed in May that year. So over a year to get a prototype and near enough 2 years from start to reaching the front line. And that was a programme that was relatively trouble free and without interference from authorities demanding changes or unable to make their minds up about the spec of the aircraft as happened to so many WW2 designs.
The B-45 was a bigger, more complex aircraft, and although its aerodynamics were conservative the jet powerplant was still new technology at the time. So with the design not starting until Aug 1944 there is no way that you could have got a flying prototype in Feb 1945 (being 6 months from the start of design). Whle I've no doubt things slowed down a bit after Aug 1945, the B-45 was still seen as a priority for the USAAF, its development was confirmed in Aug 1946 and a production contract awarded in Jan 1947 before the prototype flew in March 1947. Production aircraft didn't fly for another year and squadron service entry wasn't until late 1948, and even then the aircraft weren't fully equipped. Even f you say forget the 12 months immediately postwar, service entry wouldn't be until mid-late 1947.