At (with particular time)/ On (with a single day)/ In (with longer periods)
eg. See you at 9 o’ clock.
eg. They are returning on Wednesday.
eg. We met in 2006.
At : Home, Work, School, Airport, University, 9 0′ clock, night, noon, midnight, midday, the weekend (British), the station, the bottom
In : the morning, the evening, the afternoon, 1984, April, the spring, the summer, the autumn, the winter, the 1990s, a minute/ second, an hour/ two hours, two days
On : Thursdays, the weekend (American), Monday afternoon, Friday evening, my birthday, holiday/ vacation, time, Christmas Day, New Year’s Day, June 20, the bus, the plane, the ship
By : Car, Train, Ship, Plane, Sea, Air, Land, underground, tomorrow, next week, next month
For : a walk, a change, an hour, two days, three weeks, four months, five years, breakfast, lunch, dinner