This is a compilation of rules and explanations, based on errors most commonly made by beginner, elementary and intermediate students. However, upper intermediate and advanced students could still benefit from revising these for clarity.
Prepositions of time
Specific time: We use the preposition “at” when speaking about specific / exact time.
At 12 o’clock.
The meeting starts at 1:30 pm.
I tried calling him at 3 pm, but he did not answer.
I wake up at 07:00 every morning.
Days of the week: We use the preposition “on” when speaking about the days of the week.
Are you free on Tuesday?
I have a very important interview on Monday.
Jake will only return on Thursday.
What do you like to do on the Weekend?
Months and years: We use the preposition “in” when speaking about the days of the week.
I was born in January.
What month were you born in?
The Rio Olympics were held in the year 2016.
How old were you in 1998?
Apparently, Maria will be moving to Tokyo in March.