When is it?

Season

Act one scene four is when theres New years eve. I would expect Act one Scene eleven to be in January when its still cold and grey

Year

Just after World War One and before Nazis came into power. Before World War Two started Cabaret in Berlin in 1931 was a time were there was no discrimination and people had freedom. However it was also a time of crisis which shows in the script for Fraulein Kost sleeping with sailors. And her sharing out a flat from Fraulein Schnieder and other guests. That there was hard time and that the economy was at crisis.

Time of day

From the description of the script she's already taken men back to her apartment and they are leaving. This suggests that its the early hours of the morning. Herr Schultz is in the scene also, he works in a fruit shop during the day and he's just exiting from Fraulein Schnieders room, again suggesting this time frame would be early in the morning.