In this relationship, when would the one year mark be?

Alright, so I just found out monday that the person I had been interested in and I had dated for a month. Yup, without me knowing. I took her for coffee once and planned a movie that didn’t happen, and when I asked her if she considered the coffee a date she said no, but supposedly we dated for a month. On tuesday I asked, and after a bit of talking we are dating again from her point of view, first time from mine, so the question is, would I celebrate a one year or whatever period aniversary from that first month which I was not aware, or yesterday?