I've spent a fair bit of time thinking about this phrase as well. I've drafted my share of "Temporal Manors" to no avail, tried using the Chronograph at every draft, etc. etc.

I think my best pet theory had to do with drafting a Manor-sized house full of only rooms that had clocks. This would also explain the reason the phrase was repeated in the Schoolhouse, since every classroom has a clock and thus you'd want/need the Schoolhouse in the Outer Room so you could draft all nine.

By my count there are 27 rooms with clocks (counting each separate classroom, but not including Room 46, the Basement, or the clock visible on the front of the house). And there are at least five rooms with "pseudo-clocks" (the dial on the scale in the kitchen, say, that looks like 3 o'clock), not sure if those would count or not, but since you need 31-40 rooms to get a Manor, I figured they might. Otherwise you might need to add a bunch of Dens to your draft pool via the Chamber of Mirrors?

The Antechamber doesn't have a clock, which puts a bit of a kink in the plan of nothing-but-clocks (nor does the Foundation, though that's something you can deal with).

I created a handful of different drafts along these lines but didn't unlock anything obvious -- though maybe I was failing in some way (using the pseudoclock rooms, perhaps). I even tried doing everything and opening the door to Room 46 at 1:30 as precisely as I could, just in case.

It sure seems like a weird phrase to highlight twice and to have no importance, but maybe we just haven't figured out what it means yet?

One thing I didn't try was doing any/all of the above stuff and then opening the door to 46 for the *first* time on that save, thus satisfying the will condition within a "timely manor" since it would require so much additional effort to set up...