It is interesting (at least to me) that Golden Dawn co-founder, Mathers, gave the year 2050 as the beginning of the Aquarian Age, only 1 year later than the year you have given of the mean ingress of the age window into tropical Aquarius; Mathers used a rather unique and eclectic approach to astrology…
He may have been using the Year 1 A.D. as a starting year. According to my studies on the internet about the origin of the concept of sidereal Ages in the 1980s, this was one of the originally proposed methods around 1900, but with a sidereal 2160 year Age instead of the modern value of 2148 years.
Pure coincidence that the 1 A.D. method, which gives 2149 as the start of the sidereal Age of Aquarius due to no Year 0, is the same as this astronomically-derived start year for the tropical Age of Aquarius! I wasn't even aware of it until I found out a few years ago that Robert Hand is using the Year 1 A.D. for the beginning of the sidereal Age of Pisces and 2149 for the sidereal Aquarian Age. I calculated it as the mean setting for tropical back in 1977, MUCH to my own disappointment. I was hoping for a much earlier tropical start-date, but I couldn't argue with the astronomy.