Or never gotten off the ground in the first place...
Because Stalin wouldn't have stopped at the Elbe, but pushed on to the Bay of Biscay?
By the time the bomb was tested, Nazi Germany had already surrendered (VE Day, May 8. Trinity test, July 16). And Stalin had already agreed to get involved in Asia.
If he wanted to go all the way to the Atlantic, why did he stop at Elbe and spend time negotiating at Potsdam.