Day 0 and the acquaintance night
If there are two or more mafiosi, the game starts with an acquaintance night, when the mafia get to know each other and nobody is killed; with one mafioso there's no such night, and the game starts straight with day 1.
In short
- “Day 0” isn't a separate day with speeches; it's just the dealing of the cards, which was given a number.
- The acquaintance night happens only when there are two or more mafiosi: a lone mafioso has nobody to meet.
- Only the mafia (with the don) wake up that night: the mafiosi see each other, and everyone else sleeps.
- Nobody is killed, the sheriff, doctor and prostitute do nothing, and there's no morning summary: day 1 begins.
- If there's one mafioso, the game goes straight to day 1 right after the roles are dealt.
When there are two or more mafiosi, the game begins not with speeches but with dealing the cards. That's called day 0: nobody takes the floor, nobody can be nominated, and there's no “chaos time” either. The acquaintance night follows right after it.
The acquaintance night. Only the mafia wake up, and the don with them. The mafiosi get to know each other by looking at the players' windows. The don can show himself with his voice or a sign: there's no separate don window that night. Everyone else sleeps. Nobody is killed, and the sheriff, doctor and prostitute do nothing. With the automatic host, the mafia can finish getting acquainted early by pressing “I know my team”. With a live host, the host starts and ends this night.
One mafioso. He has nobody to meet, so there's no acquaintance night: day 1 starts right after the roles are dealt. That's how it goes at a table of four to six players; from seven there are at least two mafiosi. The exact numbers are in the “How many mafia at the table” article.