(Keep in mind I became a brony back in late July of 2013)
2010 - 2011: The rising of the Brony fandom
Well, let me start off with that I have been looking at old works in this fandom. Some like NotACleverPony, Odyssey Eurobeat, and Alex S.
This time span is where I think the rising of most of the well known brony musicians were just getting to be known. I know that there was less musicians back then but as the years have gone by I think there has been a higher quantity of musicians and decreasing quality in music. I call this the Pre-golden age of the fandom.
2012: The Golden age of the Brony Fandom
This year was the year to be a brony.