You’re all acting like he does know, he’s just not telling you. Step back for a moment and consider how things change if he actually doesn’t know and not even a

You’re all acting like he does know, he’s just not telling you. Step back for a moment and consider how things change if he actually doesn’t know and not even a water boarding session will get him to tell you how long it’s going to take. Now what? You either live with the uncertainty or fire him and replace him with somebody who can conjure up estimates - which, presumably was what you were trying to do when you hired him in the first place.