Delayed (Embargoed) "Open Access"?

It has been a shortcoming of most studies on both the extent of OA and the size and extent of the OA impact advantage that they take into account the date of publication of both the cited articles and the citing article, but not the date on which (Green) OA articles were made OA. There are already at least two kinds of analyses that show this: (1) The studies of Kurtz and co-workers on the Early Access advantage for prepublication preprints in astronomy and physics. (Earlier self-archiving does not just generate downloads and citations earlier, but that earlier usage and citation fans out into more downloads and citations overall, accelerating research not just by reaching a fixed "impact quota" sooner, but by increasing its impact quota.) (2) Brody's studies have shown that not only does self-archiving lead to earlier citations, but that higher rates of downloads early on are correlated with higher rates of citations later. http://eprints.soton.ac.uk/40867/02/chapter5distro.pdf