Photos every 6 months, ensuring the hair is the same length *and* color and that the photos are taken from the same angles, same distances, and in the same environment (preferrably as bright as possible).
Every month will drive you insane, as shedding can last a few months. The true test is how you do after 6 months and 1 year and 2 years down the road.
Those baseline photos will be your most prized posession as they will help you maintain your perspective on how you really haven't gotten any worse even though you think you have. Trust me that will be where your brain will try to take you.
Why photos instead of haircounts? Some might argue that the most important thing is how you look overall, not whether you've gone down by 3 hairs. No doubt, if someone looks at you and tells you that you're not losing your hair, that is the bottom line - even if you know you are.
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