When did the Cold War start?

Historians have disagreed on the start of the Cold War.

For those historians like Arthur Schlesinger who emphasise ideological conflict between the two superpowers, the Cold War began in 1917 with the Bolshevik Revolution in Russia.
Other historians define the Cold War as conflict between the USA and the USSR, and according to this interpretation it is the end of the Second World War in 1945 which really marks the start of the Cold War. The end of wartime cooperation between the nations, and the sticky question of what to do with post-war settlement of Germany and Europe stoked conflict. A third group of historians also view the Cold War as ‘conflict’ and not merely ideological opposition between two powers. However, they set the date somewhat later, in 1947 rather than in the immediate aftermath of World War II. Their rationale is that war was not immediately inevitable with the end of the war, rather it was the escalation of conflict with measures such as the Truman Doctrine and the Marshall Plan which pushed the Cold War from a threat to a reality.

In answering this question it is important to demonstrate that you understand that there are different possibilities, and that these are rooted in different perspectives on the Cold War. You might then defend your choice against the other options.