Who said that a conditional surrender would have to be in 1946/7? They were willing to do it in 1945, prior to Hiroshima!
As I've cited previously, there was serious opposition in the Imperial Japanese Cabinet
to surrender
after the Nagasaki Bomb was dropped. Even after that a group of Army officers attempted to seize the Emperor's surrender broadcast and destroy it, invading the Imperial Compound to do it., They then tried to assassinate the Prime Minister, Suzuki, and did succeed in burning his residence; he barely escaped.
That does
not indicate a predisposition to surrender!