A photographer is simply one who takes photographs. There is no regulatory agency that has set a set of standards or other requirements, to qualify to be a Photographer or a Professional Photographer or Amatuer Photogrpapher, such as is done with lawyers, accountants, doctors, etc. So, I'd suggest it is purely subjective as when and if you do claim to be a photographer.
My son first made such a claim in about 3rd grade when he got his own slr after showing me he understood basic exposure and composition. He actually has a better eye than I. He'd strap on the Yashica FX-3 with whatever lens he'd decide to use for whatever the day's shooting project was and load the camera with the film he decided on that moring based on research from the prior evening. He learned to read the film charts and specs; something I never bothered to do other than in a narrow way. We'd walk with the others in our group and if a stranger came up and asked about us, he'd hold up the camera and answer he was a photographer. That school year he did shoot the group class photos for each grade along side the pro that was hired and during the year photographed some of the kids and events. At the end of the year when the year book was published, a number of his photos were used.
For me the defining moment was when a class I was taking asked me to teach the class the following year as the teacher was leaving and the teacher also suggested and recommended to the school that I replace her. They reviewed some of my work as well as other applicants and offered me the basic and intermediate class in adult ed. I figured that I then qualified but never put it on my card. If I had it would have read something like: A.Sc. Business Management, B.Sc. Accounting, J.D., Certified Public Accountant, Lawyer, Real Estate Agent, Certified Mediator, Photographer, Certified by Society of Audio Consultants. I simply limited my card to the two practicing professions and used separate cards because the regulatory departments in the state prohibited listing more than one.