Why no official documentation about how to unlock Job?

[Ruanark]

Well maybe not everyone wants to level all the classes just to fund out what job(s) will came out of it? Or more likely want to get access to their (first) favourite class most efficiently ...

Best plan: level your main class required for the job you want OR CNJ to 12. This unlocks Cure, Aero, Protect, and Raise which are useful no matter what you are. Here's a list of the jobs and the required classes/lvls:

Job = Main Class + Sub Class + Cross Class*
PLD = GLD30 + CNJ15 + MRD*
WAR = MRD30 + GLD15 + PUG*
DRG = LNC30 + MRD15 + PUG*
MNK = PUG30 + LNC15 + MRD*
BRD = ARC30 + LNC15 + PUG*
WHM = CNJ30 + ACN15 + THM*
BLM = THM30 + ACN15 + ARC*
SMN = ACN30 + THM15 + ARC*
SCH = ACN30 + CNJ15 + THM*

* = Cross class, not required to unlock the job, but the job will gain some skills from this class