I've been having a tough time with that part too! If you ever find the solution, please give me a hint. (or just the answer honestly, lmao)
I haven't found it, but I can tell you what I've tried, short of just lock picking 10,000 possible combinations.
I've tried stuff like 3:40-3:50, which would roughly match the clock, even if the hand positions don't make sense.
I've tried numbers alluding to other things:
1920 - the roaring 20s.
1929 - the stock market crash.
1984 - like the novel, kind of a stretch, since this world is more business than surveillance.
1849 - the year the bowler hat was invented, due to the painting on the wall.
I've tried 9:00 and 5:00, because 9-5 working hours, right?
I've tried using rat's punch code and year of birth.
I've tried using the issue date of rat's id card.
I've tried using the real time on my desktop.
Looking at the number of protruding branches on the trees in the room, from left to right, it was a little hard to tell, but it sort of looked like 2-4-3, so I tried 2:43.
I've tried 11:59 and 23:59, which would be close to midnight, depending on if we're using military time or standard time.
I've tried the amount of money I have on me.
I haven't gleamed anything useful from what I could inspect in the room. I've tried inspecting things after changing the time, but I haven't noticed any changes.
I've tried 4:00, since 4 is written on the calendar item.
Alright I brute forced the puzzle, and now I can see where the solution came from.
Turns out the zoomed in view of the clock you get is just for looks, it's not a hint.
The solution is sort of neat, but what frustrates me is that is that the items needed for it came off as a joke items that didn't do anything, like the calendar, unless that's also needed later.
I remember the mouse at the start saying something important about their suitcase, but I also thought it was just an odd joke. I suppose that's on me for not paying enough attention, but it would have been nice for that NPC to stay in the room, so that I could hear what he had to say again considering how important his hint is.
If I had dropped the game for a day or two and had forgotten what he had said, and only had a save where I had already entered the room, I'd have to replay the whole game to get that hint again.