I think it will be great if the class guildmaster, after clearing lv30 quest, gives you one (two) new quests asking you to visit the job(s) master. At least you then understand better where they are and what they do.

Actually don't think it happens for every class. I remember the PLD job starts with the guild receptionis, but if for some reason you miss a new quest pops up somewhere else after you completed the guildmaster 30's and you are new to the game, it is more likely you will notice it only at 35, when you return guildmaster thinking to get something new.

I remember I got my first clue about jobs, just because I saw by chance a red quest marker near my guildmaster when done 30.