This source (and several others) — http://cbi-theater-5.home.comcast.net/~cbi-theater-5/victory/vj.html — says the leaflets were not dropped until AFTER the A-bomb was dropped on Hiroshima:
“Following the dropping of the atomic bomb, U.S. Army Air Force bombers dropped leaflets over the major cities of Japan. The message was plain and to the point:
TO THE JAPANESE PEOPLE:
America asks that you take immediate heed of what we say on this leaflet. We are in possession of the most destructive explosive ever devised by man. A single one of our newly developed atomic bombs is actually the equivalent in explosive power to what 2000 of our giant B-29s can carry on a single mission. This awful fact is one for you to ponder and we solemnly assure you it is grimly accurate. We have just begun to use this weapon against your homeland. If you still have any doubt, make inquiry as to what happened to Hiroshima when just one atomic bomb fell on that city. Before using this bomb to destroy every resource of the military by which they are prolonging this useless war, we ask that you now petition the Emperor to end the war. Our president has outlined for you the thirteen consequences of an honorable surrender. We urge that you accept these consequences and begin the work of building a new, better and peace-loving Japan. You should take steps now to cease military resistance. Otherwise, we shall resolutely employ this bomb and all our other superior weapons to promptly and forcefully end the war.”
It doesn’t say how many leaflets or how many cities. Another source: http://www.mphpa.org/classic/CG/CG_09B.htm
Does the book you are reading contain a photo of one of the leaflets?
I'm alive today because my Marine Corps dad didn't have to invade Japan. I'll bet I am not alone.