A helpful guide to prepositions of time

"On Christmas" is mostly American, I think. In Australian (and likely UK English too), "at Christmas" is more common, though we would say "on Christmas Eve/Day". It's the same for New Year's - "at New Year's" but "on New Year's Eve/Day".

A better (structured) guide: https://www.reddit.com/r/EnglishLearning/s/amfz6roijv

in addition to other things mentioned in the replies, a note - when using "in" for periods of time like morning/afternoon/evening you need to say "in THE morning/afternoon/evening". for night you say "at night", because "at the night" is incorrect.

Never realized how confused this must be for people who aren’t native English speakers 😭

Why does my birthday have the ‘on’ already with it? Also should say ‘the morning’ and ‘the evening’

It's 3 o'clock or 3:00, but never 3:00 o'clock. Also, for major holidays (Christmas, New Year's, Thanksgiving, Easter), you would use "at" rather than "on" (but not for minor holidays like Labor Day; Hallowe'en could go either way). The exception is if you are referring to the specific day rather than the holiday generally, e.g. "on Christmas Day," or "on Easter Sunday."

On Christmas is wrong. But On Christmas Day is fine.

This is correct but even as a native speaker sometimes I'll say "We went swimming at 6 at the night time." It happens, it's still understandable, this isn't something to sweat

Just want to add to the people saying that it should be “at Christmas” or “on Christmas Day/Eve”: in some places you will indeed commonly hear “on Christmas”, BUT it is effectively an abbreviation of “on Christmas Day” (vs. “at Christmas” being effectively an abbreviation of “at Christmastime”). If someone talks about an activity they did “on Christmas”, they are generally specifying something they did on the 25th itself (e.g., “on Christmas we ate a lot of gingerbread” implies that they ate large amounts of the treat for snacks and dessert on the 25th). Whereas if someone talks about an activity they did “at Christmas”, they are generally referring to something they did whilst on holiday during the Christmas break period (e.g., “at Christmas we ate a lot of gingerbread” implies that they were regularly snacking on it throughout the preceding and following days).

Weekend should be included, but the preposition used is less strict. I (England) always say AT the weekend or OVER the weekend. Many now say ON the weekend.

The “in” category should include durations: *in four hours, in a week, in seven years.*

This is incomplete (night, afternoon not included as times of the day) and is not general to English as spoken in most native countries (on Christmas is exclusively NAmE).

And now spin the wheel, mix it up and it’s probably still right, like on the morning of… I’ll kiss you on midnight.