SpoilerThis map again
Savant's Repose is W9.
You know that the streets get a lot rougher near the river, so you think that Cold Hole Lane would be a good place.
The docks get quieter when evening comes on, so any time after 7pm (ish) though today the docks would be clear earlier (due to celebrations) but there may be the odd person wandering about.
Lastly you realise it is a bit of a trek to the library from there. (C31-33 +C45-6)