I found the phrase 'hour-watcher' in David Shennum's English-Egyptian Index of Faulkner's Concise Dictionary of Middle Egyptian. It comes, I think, from the nown (??) wnwt which he notes as 'a division of time'.

wnwty

Gardiner's Egyptian Grammar: hour-watcher, star-gazer

There's some sort of reference to 'priestly duties' but that's all I could find.

Seme, what are the other ways to interpret the phrase? You've got me intrigued :)