The chart above shows the percentage of published US patent applications that are classified as post-AIA applications. These are grouped by application publication date. Thus, for recently published applications, about 60% are AIA applications while 40% are pre-AIA. The Sept/Oct 2014 jump occurred 18-months from the March 2013 AIA changeover date. Under US law, an application is ordinarily published “18 months from the earliest filing date for which a benefit is sought under this title.” 35 U.S.C. § 122. I expect that we will be seeing another jump in the percentages next month as US versions of post-AIA PCT applications begin to be published. (A PCT application can delay national stage filing by 30 months, and once the US national stage application is filed it takes the US a bit over 3-months to publish the application. December 16, 2015 represents the 33-month date if counting from the March 2013 AIA changeover date).
So far, there have been no PTAB or court decisions interpreting the first-to-file rules of the AIA – those issues are still churning within the examiner corps.