I mean, most FFs get a guest before the entire playable roster is finished. III, IV, VI, VIII, IX, X all did off the top of my head (you can argue about III but I feel you could make a case for Galuf in V so I figured I’d just count one of them). Of the ones not listed for the most part they don’t have guests. II could get a guest, hard to say, before Guy. XII did get everyone before a guest. And XIII doesn’t really have guests, though I guess you could count the trio of Snow’s from the very beginning. I strongly doubt they’ll show up though.
I kept silent, blaming these antics on your ignorance, but I can no longer tolerate your manners!