The Chairman of Council of Ministers of the Russian Empire, Pyotr Stolypin, having survived an assassination attempt in 1911 continued his duties. He would attempt to steer his nation away from war in November 1912 but fail.
The Balkan War was in full swing. Bulgaria was leading Serbia, Greece, and Montenegro on successful campaigns against the Ottoman Empire. Germany and Austria-Hungary were remaining relatively uninvolved in the conflict. The Kaiser was still upset over the overthrow of his friend, Sultan Abdul Hamid II in 1909. Germany would follow a policy of "free fight and no favor", allowing the conflict to play itself out. Despite Serbian gains in the area, including gaining access to the Adriatic were threats to Austrian power in the region the Austro-Hungarians did not mobilize and enter the fight.
Seeing the lack of Austrian involvement as weakness, Russian Minister of War Vladimir Sukhomlinov saw an opportunity to move against the Turks and have a chance at finally seizing Constantinople. Russia could not afford to allow the city to fall into Bulgaria's hands. On 22 November 1912 Sukhomlinov prepared plans for a 'partial' mobilization of Russian forces from Warsaw through Kiev and all the way to Odessa. They could move into the Balkans and either 'aid' the Bulgarian faction and claiming Constantinople for Russia, or they could crush the Balkan armies and seize the city anyway.
The next day, 23 November, the Tsar called an emergency meeting of his most important ministers. There were to discuss Sukhomlinov's plan and other options available. Chairman Stolypin warned against the mobilization. He felt that the Austrians would see it as a direct threat and mobilize themselves. At that point war with the Turks, Austria, and even Germany would be a real possibility.
While a number of other ministers were in agreement with Stolypin's position he was growing increasingly unpopular due to continued pushes for reforms. The same unpopularity that led to the attempt on his life a year earlier kept enough ministers from siding with him to defeat the Minister of War's plan. In a narrow decision the Tsar and his ministers decided on a partial mobilization against the Ottoman Empire and possibly Bulgaria.
Russian mobilization began 24 November (7 December 1912 Gregorian Calendar). The Austrians would react. Mobilizing their military forces to deploy against the Bulgarian alliance and to reinforce border regions with Russia, in particular Przemyśl Fortress. It would not take long for war to spread.
Information on the historical figures can be found on Wikipedia or by using Google, Bing, or whatever search engines you like. I used a couple books as reference when plugging away at this timeline:
1) The Russian Origins of the First World War by Sean McMeekin
2) Blood on the Snow by Graydon A. Tunstall