Okay. Here's the deal. You both can't be correct in your testing if your results are radically different.
If HE is wrong, and you have plaster problems as a result, you have your test results logged and you have a record of notifying him that your results differed from his. He can't blame other causes, such as what you may have done after he turned it over to you. This is important.
If YOU are wrong in your testing methods/results you should figure that out NOW, before it becomes yours to take care of. If you aren't doing the tests correctly now, you won't magically be doing them right later.
You both can't be right here and it behooves you to determine which is which before anymore time passes. You don't need to include him in your testing, but you could ask him to let you know what HIS test results are so you can compare privately. Just tell him you're trying to learn.
My PB has the same complex -- any questions and he gets all huffy. I explain to him that I am trying to learn how to take care of a pool just as I would learn to take care of a car if I'm going to own one. That seemed to settle him down. He doesn't like lawyers, engineers, or anyone who questions anything he does, so I step into the box with two strikes against me anytime we talk.

Don't get me wrong, he KNOWS what he's doing, but takes any question as a challenge to his ability. I've dealt with contractors for 29 years now so I never take anything personally.
"That's like saying "I don't know how to drive this car, but I've got a 2000 mile trip planned and I hope to learn along the way.""
I am pretty sure that with all of the reading I've done I will be able to maintain the chemistry with minimal issues. The reason that I am hesitant to test until the PB turn the chemistry over to me is that when I checked most of the levels where out of range for what plaster manufacture and the TFP recommends. When I raised my concern he was offended that I did not trust him.
Since we are still during the 30 day period that he is in charge of managing the water chemistry, to keep from getting aggravated and to help me trust him I have been reluctant to test the water chemistry.
As for learning how my pool responds to chemicals that are being added and since according to PB the plaster is still curing and this will change the effect of how the water responds and the only thing I know about what he is putting in the pool is taking guesses based on what bottles are left behind I don't believe I can learn much about it finer details.
I hope I am not being to negative sounding to any of the people here or my PB. I have seen his work and the final product is good. He just has some communication issues and is not used to his clients questioning his methods that don't always align with this site. When it comes to projects in my personal life I tend to Micro Manage ( not bad about it at work).
Also because we share a mutual friend so I have tried so for the keep things cordial when dealing with him over conflicts and so that is why I said when it comes to water chemistry right now I am going with "I think for now ignorance is bliss."
I do appreciate the people and the information on the site. I have learned a lot and probably would have not built my pool if it was not from the people and the approach used here. And I don't mean to disregard your advice but at this time not testing makes it easier to keep my hands off while he finishes up the last three weeks of build.
However, I may test the water just to practice today if I do I will post it here.