Only once the seconds

Only once the seconds
twice in thirds go
forth for a fifth of
Time - half a dozen
is still six and seven
will remain still until
the eighth moves - IF
nine is a target for all
but one on a scale of
ten - then the Eleventh
hour rests at midnight
ding ~ dong ~ dang me
with dung for teen thirteen
will bring us the fifteenth
Time to a sweet sixteenth vessel
of just seventeen, if you
know what I mean - AND
18 is enough to vote for
NINEteen when 20 is
a "2" and a zero - but
twentyone goes back so
far for me now it was
a much larger one
then, there...