The following paragraph is taken from this site:
http://agards-bible-timeline.com/q4_ad_bc_ce.html

"Dionysius named the years relating to his cycle, BC for Before Christ
which starts with year 1 and AD for Anno Domini, the year of Our Lord
referring to the year of Christ's birth.  This is also a year 1.  There
is no year 0.  That's the reason purists insists the 21st century
actually begins January 1, 2001. (for example the first year began in 1
AD and ended the beginning of  2 AD so the first year of the 21st
century begins in 2001 AD and ends with the beginning of 2002 AD)"

Since this indicates you'd have to take out both "zero years" as
depicted on a regular number line, it appears we'd have to adjust our
calculations by two years rather than one.

Like I said in my prior post, I'm officially confused!  However, with
this system, it seems like some dates I've been looking at might make a
little more sense.  Personally, I've always given myself a margin of one
year to account for the various calendar changes vs. the biblical
calendar; now I might give myself a two year margin until I have more
clarity.

Time will tell, I suppose, but by then I expect to be departed from this
earth!  Those left behind might be able to see more clearly than those
of us looking through a glass darkly.