
stackexchange.com
https://english.stackexchange.com/questions/230781…
'in' vs. 'on' for dates - English Language & Usage Stack Exchange
Dates are reported in English as being in large units like century, decade, era, epoch, period, etc, and also parts of a day -- morning, afternoon, evening; on individual days; and at individual times, plus at night. The event occurred in the twentieth century, specifically at 03:43 Greenwich, in the early morning on August tenth, in 1952.