I'd say with the pen, sooner than later. They should have allowed a couple of those younger arms in the pen to begin with. Not quite sure Burdi, Reed, Jones are ready for the show, but letting Tonkin, Oliveros, and Pressley have some extended time makes a ton of sense.
I think Arcia needs a few more weeks, though it should be clearly pointed out to him is that he needs to work a lot harder on the defense. His offense certainly isn't helping, but I'm far less worried about that long term than the fact that defense doesn't appear to be something he is working on. He's 23, and played some CF in rookie ball. There's no reason to think he cannot be an average defender.
I'd imagine Pinto will be up shortly regardless.