This is so true...I am guilty of this mistake. I am about to solve a real-life problem I have
In- long periods, future, and past...feels better now😃
On- day and dates...Your birthday passed 2 days ago!!!!---Mine is On the 25 of August.
At- Specific time or hours...Nonspecific periods of time...When In things happen at the same time.
Thank you @dansensei.
RE: Prepositions of Time: In/On/At || Learn English Grammar