You could have an earlier war coming from 1901 or 1905 but I think that is tricky. The best scenario is avoiding the spark of 1914, pushing off a war to begin between Russia and Japan over China and the lasting humiliation of 1905. That could push out to 1930 when Russia has fully built its navy or might erupt over some incident or internal Chinese fallout drawing in Japan or Russia. The question is how to sink Europe (thus the "world") into such a war. Would the Franco-Russian alliance last that long? Would the UK remain allied to Russia as she moves up to a threatening naval posture? Will the Anglo-Japanese alliance remain in place?
Perhaps the scenario is Russian aggression in Asia after 1916 with high tensions in Europe as Russia presses for advantage in the Balkans, this might alienate Britain and lure the Ottomans into the Triple Alliance, holding Italy closer, France may remain for lack of options but cooling. Japan stays close to Britain and gets closer to Germany. Taking advantage of turmoil in A-H the Russians push Serbia to a showdown drawing Germany to the brink now overconfident of its military might. Some incident sparks war in China and it flashes to Europe as Germany and Russia go to blows, France hits Germany and Italy bows out, Britain is not at war but backs Japan and lets Germany have free reins to savage Russia. Otherwise keep the Entente intact and have Japan switch sides to Germany, Japan takes on Russia during her own revolution sometime post 1916 as other predict is "inevitable." Germany goes East to take out Russia and defeating her can't conquer her with France attacking the West and Britain weighing in as Italy falls out. The reality is that you should only get one global war but not two, Japan here either succeeds or is destroyed, same as Russia, by the time they recover technology makes global war less likely, i.e. the atomic bomb.