I frequently see "they were lucky the Japanese decided to surrender after Nagasaki, they wouldn't have had any more bombs for a long time after those two. This is from the "NSA Bomb Docs" site. "4. The final components of the first gun type bomb have arrived at Tinian, those of the first implosion type should leave San Francisco by airplane early on 30 July. I see no reason to change our previous readiness predictions on the first three bombs. In September, we should have three or four bombs. One of these will be made from 235 material and will have a smaller effectiveness, about two-thirds that of the test, but by November, we should be able to bring this up to full power. There should be either four or three bombs in October, one of the lesser size. In November there should be at least five bombs and the rate will rise to seven in December and increase decidedly in early 1946. By some time in November, we should have the effectiveness of the 235 implosion bomb equal to that of the tested plutonium implosion type." Rough math says dozens of atomic bombs would have been available for Operation Coronet (March 1946), less those used in Olympic (November 1945). https://nsarchive2.gwu.edu/NSAEBB/NSAEBB162/45.pdf, page 2.