Preposisi Waktu: IN, AT, and ON

The preposition in, at, and on are used in time expression as follows:

In the past, in the present, in the future, in the morning, in the afternoon, in the evening

(a) Please be on time in the future.
(b) I usually watch TV in the evening.

At noon, at night, at midnight
At + "Clock time"
At present, at the moment, at the present time

(c) We sleep at night. I was asleep at midnight.
(d) I fell asleep at 9.30 (nine-thirty).
(e) He's busy at present. Please call again.

In + a month/ a year/ a century/ a season

(f ) I was born in October.
(g) I was born in 1975.
(h) I was born in the twentieth century.
(i ) The weather is hot in (the) summer.

On + a date/ a weekday
On + weeakday morning(s), afternoon(s), evening(s)

(j ) I was born on October 31, 1975.
(k) I went to a movie on Thursday.
(l ) I have class on Thursday morning(s).

Source: Fundamentals of English Grammar by Betty Schrampfer Azar