Preposition use — in / at / on — prepositions of time and date

IN

Use 'in' months and years and periods of time:

in January
in 1978
in the twenties

Use 'in' a period of time in the future:

in a few weeks
in a couple of days

AT

Use 'at' with precise time:

at six o'clock
at 10.30
at two p.m.

ON

Use 'on' with days of the week:

on Monday
on Fridays

Use 'on' with specific calendar days:

on Christmas day
on October 22nd

IMPORTANT NOTES

in the morning / afternoon / evening — at night

We say in the morning, afternoon or evening BUT we say 'at night'