I have no idea what this sentence could mean, except if some couriers carries a package with a clock, and deliver it to a customer at the right delivery hour.
Could it be an idiom for "the clock keeps time"? - but I suppose if it were Duo would have told us.
Finally, now the fifth soldier will have his clock!
(From: Quintus miles horologium non habet.)
I was wondering why tempori (dative) is used here. Anybody any idea?
I think it's not the dative, but only an adverb that has the same form that a dative.
Maybe it's derivated from the dative (to the time?), maybe not. But it's not the dative anymore, it's a fixed invariable form, as all the adverbs.
If you add "always",
Horologium semper tempori advenit.
You get a deep philosofical saying. ;)