There wasn't really one point in time when the vernacular started being used and Latin fell by the wayside. Even in the 19th century, formal exams at many European universities were still being conducted in Latin.
On the other hand, translations of the Bible into the vernacular date back to the time of the Ostrogoths, bishop Ulfilas translated the Bible into the Gothic language around 350 AD.
Literature in the vernacular is quite old as well: Beowulf for Old English (earliest date 8th century), Scandinavian sagas (start around 1000 AD), Old Irish verse dates back to the 7th century, French troubadours and German Minnesinger travelled around singing in the vernacular, romance literature such as Chanson de Roland (circa 1100 AD) was composed in the vernacular, the Nibelungenlied dates from around 1200 AD, etc.
Scholarly works emerge quite early as well: the Anglo-Saxon Chronicle is a historical text in Old English dating back to the 9th century. Old Irish was used for historical texts as well as commentaries on Latin authors as early as the 8th and 9th centuries.
Interlingua speaker here. The Interlingua translation, for one, is full of spelling and grammatical errors. So I would take the other ones with a grain of salt as well.
Edit: A better translation of Genesis in Interlingua is here.
>1 Tote le terra habeva le mesme linguage e le mesme parolas. Quan-
>2 do le homines migrava del est, illes attingeva un valle in le
>3 pais de Shinar e se establiva ibi. Illes diceva le unes al alteres, 'Veni, que nos face briccas, e los coce dur'. Le briccas
>4 les serviva de petra, e le bitumine les serviva de mortero. Alora illes diceva, 'Veni, que nos construe nos un citate, e un turre cuje apice es in le celo, pro facer nos le renomine; si
>5 non, nos essera dispersate super tote le mundo'. Le Senior descendeva pro reguardar le citate e le turre que le homine habeva
>6 construite, e le Senior diceva, 'Si, como un gente con un linguage pro omnes, illes ha comenciate a facer assi, alora nihil que illes se propone essera foras lor attingimento. Que nos descen-
>7 de, alora, e confunde ibi lor parola, quo le unes non comprende-
>8 ra le parola del alteres'. Dunque le Senior les dispersava ab ibi super le facie de tote le terra; e illes cessava de constru-
>9 er le citate. Pro isto on le appellava Babel, proque ibi le Senior confundeva le parola de tote le terra; e ab ibi le Senior les dispersava super le facie de tote le terra.
Looks like the english translations are copyrighted by other entities, according to this discussion, the German version seems to be out of copyright in the USA and Canada. Interesting.