For more details of that little-known Feb 20 paper by Chinese scientists that calculated a likely start in November or even earlier, see:
Last, for a review of the various counts, official and through leaks - including the CDC papers seen by the SCMP, see the Silent Numbers (I keep updating this).
Notice that there are multiple tabs.
- The SCMP tab is SCMP_Mar20.
- Check the CDC tabs too.
Also here is a thread that takes in the China-WHO report and some of the issues with the CDC data, especially around jump on the 1st Jan 20.
The 1st Jan is the day the WHO decided to activate Article 10 of the International Health Regulations which started an incident management process.
A formal request for information under Article 10 had to be sent on the 3rd Jan.
See the timeline: