Six minutes for Olynyk? Zero for Pressey? Fire Stevens!
Once Rondo is at full strength, how many minutes do you envision for Pressey (assuming it isn't a blowout... which may not always be a great assumption...)
Considering our current depth at PG, and that this will most assuredly be a "player development" season, I would expect Pressey to get fairly regular, though not major, minutes backing up Rondo. I expect that Rondo will average fewer minutes per game than he ever has this season, since he's coming off a major injury and the team isn't going to be focused on winning (lots of blowout losses).
When we've got a reasonably set rotation I think you'll see Pressey out there for anywhere between 8 and 16 minutes a game, for better or for worse. I'm pretty sure he'll be a more capable point guard than Bradley or Crawford is likely to be.