If you prefer to watch a video instead of reading the guide, feel free to do so. There is a playlist that covers every trophy on my YouTube channel. If you'd like and subscribe or even become a member, it would mean a lot to this channel!
Day One is a tutorial and takes about an hour of game time. The mystery cannot be missed.
After waking up you meet all the guests in the Atrium. The first mysteries of the day are Mister Toussaint and Missus Erickson. After that the game opens up and you can investigate in any order. If you want to do a blind playthrough first, ask every new guest about their timetable, because it is blank before you learn it.
Most of the main mysteries and guest cases can be started on Saturday. The masked ball at 9:00 PM cannot be skipped.
The Basement opens on Sunday and unlocks the remaining cases. Solve as many cases as possible before you enter the Blake Residence, because the number of saved guests decides which ending is available.
This is the point of no return. Make a manual save before you enter the Blake Residence.
The second playthrough takes roughly 40 minutes as we have only two trophies left to focus on.