Here's the report for this day, August 1, in 1945.
Includes this: "Today he [Truman] gives a letter to Stalin, which confounds him. Earlier, Stalin had promised to declare war on Japan around August 7. Now Truman writes that more consultation is needed. Truman had pushed for the entry, writing in his diary "fini Japs" when that occurred, even without use of The Bomb. Now that he has the bomb in his 'pocket' he apparently hopes to stall the Soviets."