Originally Posted by
EiraWoqiso
Fates and S rank hunts do have a trigger. The only ones that don't are B Ranks (respawns in ~5 seconds iirc) and A ranks, which are usually left alone for a hunt train. You don't really have to worry too much about 'right place' as much as 'right time', basically just don't be busy when things are nearing cap. I don't know how things work over on Hyperion, but on Cactuar we typically recommend joining a Hunt LS and if you're worried about missing a train, check in the LS when the last train was. Usually a train won't start until ~5 hours after the previous train at the earliest.
Fate bosses have manual triggers typically tied to fate chains, although some older fates were also tied to zone weather. S Rank hunts ARE manually spawned, through a variety of means, and standard etiquette is to call the hunt to hunt LS and wait until the spawners pull, but early expansion there's so many people that they get anxious and pull early. There's been requests to make FATE bosses and S ranks have a few minute invuln timer to allow everyone to arrive and join a party, but that's unlikely to happen.