Hello. I just bought the game yesterday and I'm having a blast. I'm confused on the black mage job tho. I created a Thaumaturge and I understands that I need to get it to level thirty and a level 15 Archer. SO do I level my current character to thirty and then log off and create an archer to 15 then I can log off and make a black mage or what?

Or do i level Thaumaturge to 30 then change it to archer and level it? I'm confused but not sure about all the jobs and professions like alchemy and goldsmith. I tried google but can't find much detail.