Usage of preposition "of"?

[nordway]

Hi, are these two cases of using the preposition ‘of’ too exotic or they are real? I found them in the Longman dictionary.
The first one.
22 American English spoken used in giving the time, to mean 'before' synonym 'to' British English
It's a quarter OF seven (=6.45). Instead of It’s a quarter TO seven.

The second one
25 of an evening/of a weekend etc British English in the evenings, at weekends etc:
We often used to walk by the river OF an evening.
Instead of
We often used to walk by the river in the evenings.

[DavidAmes]

"Quarter OF seven" is the preferred American usage.
"A quarter of seven" is much less common.
Instead of "of" you may hear "till" or "until" or "before."

"Of an evening" might be interpreted as occurring frequently.
It has a literary taste.