When Julius Caesar introduced his calendar in 45 B.C.E., he made 1 January the start of the year, and it was always the date on which the Solar Number and the Golden Number were incremented.

When did years begin to be counted?

The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table.

When was the first year ever?

AD 1 (I), 1 AD or 1 CE is the epoch year for the Anno Domini calendar era. It was the first year of the Common Era (CE), of the 1st millennium and of the 1st century.