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

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

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

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

Same here.

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

Is it normal to feel worse before better? Nobody told me that.