Having read multiple books regarding the Chinese Revolution, the start of the 2nd Sino-Japanese War seems to be a better fit for the start of World War II rather than the invasion of China. The Marco-Polo Bridge Incident, widely considered the beginning of the 2nd Sino-Japanese War, had far-reaching consequences that are rather under-appreciated by much of the general populace of the West.
This war would initially sway public opinion in the US, and the rest of the allies, against Japan, and eventually cause trade embargoes to be enacted by the allied powers. It can be argued that these embargoes led to an accelerated invasion plan from the Japanese and the eventual attack on Pearl Harbor.
Though it initially did not involve the two largest powers of World War II, this conflict ultimately became the Pacific theater of war for the Americans, who were eventually joined by the Soviets with their invasion and occupation of the Japanese puppet-state, Manchukuo. Given the history of Russo-Japanese relations, even without the agreements of the Tehran Conference, this seemed likely to occur, as their had been numerous Soviet-Japanese border skirmishes in the years preceding.
Is the fact that this is not seen as the start of World War II simply due to the largely Euro-centric historical views taught in American school?
For what is worth the United Nations does place the beginning of WW2 in 1937, with the Marco Polo Bridge incident.
However, for a war to be a world war it has to be fought, well, worldwide. China's conflict with Japan was only fought in China. When France and Britain declared war on Germany after it invaded Poland, they had the capacity to wage war everywhere thanks to their colonial empires. Take the 1939 Battle of the River Plate off the coast of Uruguay for example.
It was accepted that World War II started in 1939 because what was used to be a one-front war (Asia started by the Japanese) turned into a two-front war, thus starting the world wide conflict that got many nations (including Latin American countries) involved. After Pearl Harbor, American, British, French, and Dutch colonies in the Far East were overran by the Japanese while they were fighting the Nazis in Europe. North Africa was fought between British and its allies and the Nazis and the Italians as most of them possessed colonies in that continent too.