It depends again on many factors, mainly how CIO is dealing with them.
For example till mid-august applications, they charged cc and ECAS was updated just 2-3 days before PER. That means after CC they did not touch the files for 2 weeks. (My cc was charged on 16th Nov, ECAS was active from 29-Nov, PER 2-Dec)
After that from early Sept, they charged CC very fast, all the Sept CC were charged in the span of 1-2 weeks. And their Ecas was active for 2-3 weeks (some cases even a month) before PER received.
So, the actual procedure is, CC will be charged first after completion check, then someone will enter ur file detail to compute system (by scanning the bar code generated) and keep it for review by office. Now, it depends on the officer, number of files already waiting for review and complication of ur file.
The PER email can be delayed if one officer is not satisfied with something. If so, he cannot directly issue NER, he has to send it to another officer to confirm if it is NER, the other officer (superior) will issue either PER or NER.
I hope its clear