Is a baseline blood test really necessary before starting something like this?

Sorry for the basic question, but how do you actually start one of these diaries?

How long before you can reasonably say something is or is not doing anything?

Following this because I am in the same place and have no idea what to ask at the appointment.

How do you tell the difference between the drug working and just a good week?

Is a baseline blood test really necessary before starting something like this? Tolerance was my main issue with whey protein too.