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

You have two changes at once here. You cannot attribute anything until one of them moves. Same for me with a billing error, unfortunately.

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?

Careful with attribution. You changed the timing, the dose and the season. That is three variables.

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

What do you do about the fee? Do you just pay it?

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