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?

Did not know half of this. Thanks.

Do you contact the customs office or the carrier first?

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

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

What is the first thing you would read if you were starting from zero?