when you create a character you make 1 an archer 3 thaumaturges...... wow. If you made 4 archers take 3 of them after they do the lvl 10 archer quest and talk to the thaumaturge trainer and learn to be a thaumaturge. its not rocket science. You want 1 archer 3 thaumaturges and then at lvl 30 you unlock Bard and BLM. Bard=30 archer+ 15 Pugalist, Blackmage = thaumaturge30+15 Archer. You have to do the class quests from 1-30 to unlock each job.
Class=archer,thaumaturge
job=bard, blackmage
Class=archer,thaumaturge
job=bard, blackmage