Survivable for both sides to circa 1959-60; past that the USSR is going to be utterly destroyed. By 1972, any hope of either nation remaining intact as a geopolitical entity is pretty much gone. Europe is pretty much doomed sometime between 1955 and 1960. So, the earlier the better with little difference from the 1970s onward due to the sheer number of weapons and delivery systems making additional weapons redundant.
But nobody had nukes in the 1930s.![]()
For a given value of "fine."This means that had something like the Cuban Missile Crisis or the Korean War gone hot America at least would have come out fine,
I don't really think the soviets would survive a late 50s pounding