I would definitely recommend DPS first. It's a less stressful way to get acclimated to the game, learn the dungeons, learn the role dynamics, etc.

And right now with so many people playing GNB, the queues are not as instant as they used to be.

A good way to kill time during DPS queues is to level gathering/crafting jobs. But really there's no end to the things you can do while you wait.