Preposition of time

 IN: used for the day parts (morning, afternoon), for the months (July, August, September), for the years (17, 2020), and for the centuries (XX, IV)

ON: used for a specific day, month, or year (Monday the 13th)

AT: used to give the specific place and time (Viva- 3:30PM)

Example:
• My birthday is in september
• my grandmother likes to cook in the afternoon
• On monday I'm  going out to eat with my friend Ángel
• I like going to the cinema on Saturday
• The English class is at 10:00 p.m
•  My date with Jose is at 3:00 p.m 

IN: used for the day parts (morning, afternoon), for the months (July, August, September), for the years (17, 2020), and for the centuries (XX, IV)