It may have been his first paper on the wave nature of light, but it wasn't his first paper. He had already written on capillary action (1901) and several papers on thermodynamics (1902 - 1904).
In fact his paper on brownian motion "won him a PhD from the university of Zurich." (
http://www.space.com/reference/brit/einstein/life.html)
Einstein was a recognized genius by the time he published his paper on the photoelectic effect.
One very weird thing about his SR paper, published a little later in the year, in Annalen der Physik is the sparcity of bibliography. There were *NO* references in his paper on SR. (At least not in the translations I've seen.) It's just right out of his head.
The site above refers to his alma mater as "the renowned Federal Polytechnic Academy in Zurich." (Of course, any goof can write an 'authoritative' looking website. Maybe this is an exaggeration. I don't know... but the site at least claims that the article is from britannica.com)
I'm not sure it's true that his paper was "not considered important for many years." It may not have been important to the general public, but I think many of the leading scientists had at leat some understanding of its significance. From the above site: "Public understanding of this new theory and acclaim for its creator were still many years off, but Einstein had won a place among Europe's most eminent physicists, who increasingly sought his counsel, as he did theirs."
