The October Revolution could have happened in early May from a simple POD. What does this mean? Well, the balance of power was different, so maybe a different leader and regime. Russia would be out of the war by the early summer, which means perhaps the Germans could launch a Summer or Autumn Offensive by pulling back divisions from the Eastern Front. This could be decisive in ending the war with the Central Powers claiming victory.
There was significant outcry in the reshuffling of the Duma, after Miliukov proved to have imperialist designs on Galicia and the Bosporus Strait and in general supported new offensives on the Eastern Front. It was almost unanimous: even the Allies wanted him out of the position of Minister of Foreign Relations. Who to replace his seat? Significant thought was given to Victor M. Chernov, the head of the Socialist-Revolutionary Party, who had effectively brought this information to the attention of the public. In OTL, there was a last-minute decision to make him Minister of Agriculture and give the Ministry of Foreign Relations to a non-socialist who would be liked better by the Allies, Tereshchenko.
The problem with Tereshchenko was that Miliukov actually recommended him for his replacement, and he differed only in his methods, not motive. He was part of the "defensist" and even the "pro-war" faction. Soon this would be discovered, but not in the last days of April.
Let's say that Chernov is able to maneuver himself into the position of Minister of Foreign Relations, or maybe Tereshchenko dies, or is assassinated... there are numerous PODs on how it could have happened. It isn't likely, but there was a chance it could have happened. The new cabinet is established on May 6.
Victor Chernov becomes Minister of Foreign Relations and begins appealing for "peace without annexations or indemnities". He is, of course, on the left-wing and for immediate peace. This creates tension with the Allies, but mainly the defensist/pro-war factions in Russia, especially in the Provisional Government. Pretty soon, the right-wing and non-socialists of the Provisional Government resign and begin mobilizing 'White forces' for a counterrevolutionary movement. Every party splits between pro-war and anti-war sides. In this atmosphere the Bolsheviks are definitely the strongest, but not as much as in October.
So, there is a crippled, much more illegitimate and ineffectual Provisional Government. Nevertheless, let's say that by June 22, an armistice is signed with Germany and the Central Powers and peace negotiations begin. However, the Petrograd Soviet and other soviets are gaining much more legitimacy and power, with even Chernov saying that his party should concentrate on focusing their efforts through the Soviet system. A huge number of soldiers begin leaving for home, increasing participation and activism in the soviets.
Under Victor Chernov as Foreign Relations Minister, instead of Trotsky, I can see by July 17 a Peace Treaty being signed which hands over all the territories Germany holds currently... unlike Trotsky, Chernov would not make for 'delaying action' in the negotiations, nor would he be so obstinate to walk out. Germany formally establishes military command over Poland, Lithuania, and Courland (western Latvia).
It is this that lights up the July Revolution. Many, even anti-war factions, paint Chernov and the Provisional Government as having failed. Chernov most likely resigns and Vladimir Lenin declares it a good time for the Bolsheviks to seize power. Kerensky won't give up his spot, and will put together a revolt (with Kornilov and other White generals) that could more or less succeed. With the Soviet trying to claim supreme power, the Cossacks rise up, as well as monarchists. The Red Terror begins, which causes more Whites to join reactionary armies.
On August 4, 1917, the Third Battle of Ypres, or the Battle of Passchendaele, is ongoing... but it receives an extra 70 divisions (50 divisions as they gained with peace on the Eastern Front in OTL, and another 20 divisions freed up from occupying Latvia, Estonia, and Ukraine). Now, a lot of key tactics haven't been fully established: stormtroopers, Hutier tactics, the Feuerwalze artillery bombardment, so it won't be a clone of the Spring Offensive, but really wrap your head around 70 extra divisions. Sure, the Germans are playing defensive action... but that gives them more time to train stormtroopers. The Germans could very well launch a counter-attack on August 4 and take as much territory as they did in Spring 1918 by November 1917. The Germans could likely control Paris by Spring 1918, in which case the French would most certainly sue for peace.
By October 1917, you have Allied occupation of Archangelsk, Murmansk, and Japanese intervention in Siberia, with White forces intensifying in power, about nine months sooner than OTL. The Soviets would likely be controlled more by the Socialist-Revolutionaries than IOTL, but the right-wing SRs would be dismissed, and Chernov would be trying to rebuild his influence, likely to be overtaken by Vladimir Lenin. Lenin will probably once again take over power very effectively and absorb the fragmented SRs into the Bolshevik Party.
What does this mean in the end, again? Well, a Central Powers victory, surely, although it won't include the Ukraine. I expect the Allied intervention will be more ruthless, though perhaps shorter if the Central Powers win quickly enough... the Allies could very well try to sustain the Soviet Union as a bulwark against the Central Powers at that point. Nevertheless, the White forces will have German and Austrian support, which is huge. In fact, I predict the White forces taking Moscow... the Central Powers would not risk the survival of the Soviet system and would poor a lot of money into it.
Still, I'm not looking at it all very closely. What are your thoughts?