1946-47 if the US chooses to invade instead of dropping the bomb.
Lets assume no A Bombs. lets assume the European war went 3 months longer(almost ASB in itself-although with some sensible defensive preparation the Nazis could have made it last maybe 3 weeks or so more).
1947 is a fantasy. Starvation well before then. They lasted until August 1945 OTL. It was widely known that not just hunger, but starvation itself was only 2-3 months away at the current rate of progress. Lets say November. With Okinawa fallen, the heavy bombers would have nothing now to focus on except the home islands. British and Soviet forces could and would have joined in. Submarines and aerial mining. More city firebombing and more homelessness. OK so food stocks run out November. Taking into account the stoicism that was shown by the average Japanese soldier and transfer this to a civilian population that was already fatalistic as to their ultimate fate. That makes it Jan-Feb 1946. It pretty much can't last past that. Worse still, by that stage(in fact probably by November-December), they will have lost their ability to hurt the allies, even via suicide tactics.