It is 1913: the last peaceful year of Imperial Russia, before the advent of the age of war and revolution.
The characters don’t know what’s coming, but something is already in the air.
This page describes Russia and St Petersburg in 1913, and provides a very rough overview of recent history.
Description is written in the form of “hot topics”, which you can use in-game as conversation starters.
You’re welcome to read more about the era and use your knowledge in-game, but please be generous towards your fellow players, and remember that they might not know everything you do. So, instead of saying “What’s your analysis of the Russo-Japanese War?” you could say something like “It’s already been eight years and I still haven’t gotten over the fact that Japan completely humiliated us in the war! You’re just back from Paris – tell me, please: are they still telling jokes about us losing the entire Pacific AND Baltic fleets?”