A rollout that began on September 23, 2016, it looks like the Google Penguin real time algorithm has finally rolled out completely to all of Google’s data centers.
This is something that has been confirmed by Google’s Gary Illyes on Twitter:
@jenstar yes, eh
— Gary Illyes (@methode) October 13, 2016
The recovery aspect of Penguin 4.0 began shortly after September 23 – around September 28. With all the data centers upgraded to Penguin 4.0, those sites impacted by previous Google Penguin problems should have seen a recovery at some level if the necessary steps where taken to clean up their links.
Keep in mind that, if you didn’t know already, Penguin will look at the link source for the most part, so if there are spammy links pointing to your site, take care to clean it up.
If you were hit with any version of Penguin before 4.0, you should begin seeing an impact to your rankings if you made link clean up efforts.