thank you selene and megli,
i, of course
, want to get (respectfully) critical here, which i hope will be taken in good part! (i mean well!!!
In 33 AD (or thereabouts) Old Irish didn't exist yet. The earlier form of 'in ri' 'the king' was *sindos rigs in Primitve Irish.
megli, do you derive this belief from the study of texts only - corpus etymology? surely you're aware that this is considered, rightly i think, to be very misleading.
not only is arriving at an accurate chronology for very old texts difficult and current chronologies tentative and inconclusive, especially when based on linguistic forms used in otherwise undatable texts, such as those of most of those referred to as proto- or primitive are, but even if you have a sequence of accurately dated texts from older to more recent, it is probably impossible in most instances to prove that the language of later texts represents a direct evolution from the language of older texts.
for example, throughout the gaulish speaking world at the time of the roman expansion there must have been many different dialects from galatia, through galilee, cisalpine gaul, france, spain, and britain to ireland, and there must already have been considerable diversity.
the texts which have survived the destructions of texts that used to be a routine part of conquest are fragmentary and few and many have fetched up far from home, with the result that their histories including their exact ages and even country of origin, are now not known.
so the language of a text currently classified as 'old irish' is not necessarily a direct evolution of the texts currently classified as proto or primitive. it might have evolved from a concurrent language easily recognisable as old irish as which has left us no textual examples but was widely spoken.
what i'm trying to say is that while examples of texts are classified as primitive irish because they differ greatly in specific ways from texts deemed to be older, the vast mass of spoken language can no longer be consulted. but they should always be kept in mind. old irish might be as old as ancient greek, ancient hebrew, ancient latin, with the few fragmentary texts you call primitive irish representing not an ancestral form of irish but (a) now extinct contemporary sibling language/s that differ/s not becaue of chronological but because of geographical and/or demographical factors.
i don't believe you can fairly say more than that we know of no examples of old irish that can be dated with any certainty to the 1st century, while acknowledging that very little is known about ancient languages outside of texts - and not
that we know that it didn't exist. what languages were the irish people who left no texts speaking at the time? only one? only the one we have textual traces of? maybe, maybe not. i don't believe you can make such an assertion.