Edgar Ruiz describes an approach to make determinations of what the CRAN flow and timing looks. He writes
The approach was to record snapshots of the CRAN Incoming folder contents in a regular interval (ftp://cran.r-project.org/incoming/). Inside the Incoming folder, there are sub-folders that equate to the status in which the package is at that time. Knowing when a given package enters and leaves a sub-folder, and where it goes after that, provides the information that we used to determine direction and duration of each package movement.
https://github.com/edgararuiz-zz/cran-stages
Hadley Wickham distilled these findings into a diagram.
Again, please note that this diagram is based on assumptions based on snapshots of the Incoming folder. This is not the official CRAN process, just an analysis to help derive the current process:
https://github.com/edgararuiz-zz/cran-stages
More on Edgar Ruiz’s github project: https://github.com/edgararuiz-zz/cran-stages