I'm sure in history not all cultures started recording time simultaneously, so when did it happen?
You mean, when did people start using the birth of Jesus Christ/Jesus of Nazareth as the reference to the "year 1" of the common era?
hi! fyi, in the FAQ, you'll find loads of info on the evolution of the calendar most of us here in Reddit use today, and some info on adoption across the world (where it is still not the primarily calendar in some places), and some info on other calendars. There's lots of room for more info on adoption by various cultures, but this should get you started