[loucon]

I use the date of the 1st fatality within a given region minus thirteen days. That should be close (plus or minus a week).

[CatOwner]

I wonder when we really had the first exposure to COVID-19 in the CONUS?

[Valpal1]

That totally fails to account for mild cases that may have been raging for weeks or months prior to reaching the more susceptible population which tends to not get out as much.