Anyway, even if American scientists knew exactly which avenue of research to take to develop the bomb (instead of investing in all of them) I don't think they could get The Bomb much earlier than they did. Six months earlier maybe?
Even after over 60 years, it's sad to see how little people actually understand about the Manhattan Project.
The scientists and engineers involved did know exactly what was required to build an
uranium bomb. Some final calculations were needed regarding critical mass, but the uranium bomb was such a no-brainer that the design wasn't even tested before it was dropped on Hiroshima.
Manhattan Project invested all that time and all those resources in other avenues of research because they were profoundly aware of something of which too many people today have no clue: there wasn't enough U-235 on hand to make multiple bombs and there wasn't an "easy" way to get anymore.
In 1945, the Hiroshima bomb used something north of 95% of the world's then current supply of U-235.
The Manhattan Project primarily investigated and developed the production and use of fissionables other than uranium in weapons. Oak Ridge was built to produce the U-235 needed for Little Boy
and the Hanford breeder reactors which produced the plutonium used in the Trinity and Nagasaki bombs. The "gun slug" mechanism used in the Hiroshima uranium weapon was quickly shown to be unsuited for plutonium, so the Project had to devise, develop, test, and produce another mechanism for plutonium use.
If the US foresaw the need for one bomb and wasn't interested in serial production of the weapons for years down the line, it's quite possible that an uranium bomb could have been dropped in late 1944.
Bill