Huzzah! I obtained sub-classes! Managed to obtain the Magicked Skull with the first ghouls I spawned for the evening. Unfortunately for me, it looks...
Alternatively, if you continue to have trouble with getting the subjob that way, the Rhapsodies of Vana'diel storyline provides a key item very early...
Hah, I was just thinking this morning that if we were going by recent FF history, i.e. the last twenty years or so. Then FFXVII should be another MMO...