This made me think about the differences between the logistics of the surrenders of Germany and Japan. Germany surrendered in seven days after the death of Hitler, while Japan surrendered in 17 days after the rescript of Hirohito. I can think of three differences off the top of my head, and it would be interesting if others here would be willing to point out any others...
1) There wasn't much left to surrender by the time Hitler died; Germany was essentially overrun, so outside of the U-boats and a few Nazi units elsewhere, it wouldn't have taken long to get the surrender set up. By contrast, Japan still had a far-flung military presence, often without supply lines and without communication (remember, the last Japanese soldier surrendered in 1974), so it's not surprising that organizing the surrender would take longer.
2) By the beginning of May, there weren't many Nazi leaders left: Doenitz was the Fuhrer, but all the rest of the inner circle was either dead (Hitler, Goebbels) or heading for the hills (Himmler, Goering), so it was easy to point to Doenitz and make him make the decisions necessary. By contrast, all of Japan's leadership was fully involved and fully available, so it took the better part of a week to assemble a government that could surrender without the Emperor himself actually participating openly in the surrender, plus going through all the nemawashi of getting everyone on board. One of the effects of this, BTW, was that Japan's occupation went far more smoothly than Germany's--not only because of the lack of Soviet involvement (thank God), but because with extremely few exceptions, the Japanese co-operated with the occupation from beginning to end.
3) August is typhoon month along the ring of fire, just as it is hurricane month in the Atlantic, and there seem to have been more typhoons than usual in 1945--the fact that they had already gotten as far as U(rsula) by early September shows this. The only problem with Europe's weather in the spring of 1945 was that there was more rain than usual, which slowed down the Brit/US invasion from the west, if not the Soviet invasion from the east.
I am thinking American logistics. There will be large numbers of dignitaries and high ranking brass on the Missouri; thus it was essential to have American military control over the surrounding region to prevent any "hot-head" from attempting a kamikaze attack or fire guns at the ship. To do that we had to move a large number of ships, planes and support units to Tokyo. It would take some time to do the staff work to redirect missions and get the troops and all their stuff on the ground before ceremony can take place. Because of the devastation of the region, we couldn't local source anything, and would have to stretch our logistical tail to Tokyo and Sagami Bays.