One more thought.
If Japan does not attack any Allied Power through Japan’s first three turns it’s possible, although very unlikely, that it will only be at war with United States at that point. If Britain/ANZAC refuse to commence hostilities against Japan and Japan does not attack them or the Dutch either, only the U.S.A and China would be at war with Japan come round 3.
My point is… maybe the British/ANZAC player should be patient (if possible) and let Japan attack first– because a Japanese attack automatically brings America and its huge income into the war, too.
If Britain and/or ANZAC attack Japan first, Japan can retaliate without provoking the U.S, therefore limiting the U.S IPC income until round three.