This question was migrated to Music Fans SE: In the Mass Ordinary, what are the words that should be set to a fugue?. The original title for the question was "What are the words for the Gloria fugue?"
Both titles are unfortunate and misleading, because the actual question was:
In setting the Mass Ordinary, what are the words that should be set in a fugue? "Cum Sancto Spiritu in gloria Dei Patris" or just "in gloria Dei Patris"?
The OP knows the words already - the words he quotes are the last words in the Gloria, and they're usually set off as a section by themselves which frequently features fugal writing, so the question he is asking is where in the Cum Sancto Spiritu section does the fugal texture start?
That's not unlike asking where in a sonata the development should start (allowing for the fact that formal divisions in a Mass are tied to the words), and thus, as far as I can tell, it's a question about compositional form that is well within our remit, and well outside the remit of Music Fans SE (and it has been drawing comments in Music Fans SE to that effect).
What was the rationale behind the migration?