We set off at almost five o'clock or we set off almost at five o'clock?
'The goldfish tapped the glass with his head.'Is there a more appropriate way to say that?
We set off at almost five o'clock.
"... at 5 o'clock" is a specific exact time.
"Almost" is a modifing adjective.... It makes the specific Not Exact. Adjectives are placed before the noun. "at" is a preposition which is always placed before adjectives.
The goldfish bumped into the glass with his head.