Carver seems to level up a bit too fast compared to the other characters, so this makes job grinding a little tough. However, once you make you're way to a place in the game called the Spiegelspire, there is absolutely no level cap( meaning that you could be level 80 or higher and still come back to this place to job grind). Here's the recommended party:
Have the Hero, Milly, and Ashlynn cast the Boom spell. It only takes the Hero's and Milly's to take the entire opposing monsters out. Combine this with as the battle ends having someone use the Whistle ability and this becomes an excellent grinding place! This area works great if you're trying to get to the advanced classes early.