Okay so regarding to the book, I played the game again to test it out, here is what I found out:
Check the DAY number when you order the book (Time doesn't matter), then you can go talk to the receptionist the day after (Day of order + 1 )... for example:
I ordered day 4 ... I have to talk to the receptionist at day 5. or else the receptionist might bug out and wont give you the book and you will be stuck with that part.
Although the book is not really important for now, but I'm assuming for future updates it will be.
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Regarding Day 11 in the walkthrough (also day 8), I said to wait till 23:00 because:
1. There is nothing new to do, it will be just repeating old stuff you already have seen. Feel free to repeat them by yourself.
2. there is no benefit in repeating the same actions and I'm trying to reduce the time it takes you to complete the game.
Day 12 should be the last day you play, as there will be no more new actions to do or new CG to look at. Plus with a new update you will be most likely to repeat older days so, your efforts will be wasted, and I don't want that