That paraphrasing is incorrect. It's actually the April before that (2019). Also according to that article Tesla didn't "announce" that. If you dig into the article it claims the following:
"Before the on-road demo, Tesla engineers .... Tesla expects that to happen by the end of the year, and in 2020 Tesla will launch a car-sharing program in select cities including San Francisco and New York, in which owners or lessees can join the Tesla Network and loan out their autonomy-enabled vehicles when otherwise not in use."
Will Tesla’s Robotaxis Come to Its Rescue? | Automobile Magazine
His "1 million" claim is referring to the amount of cars with the hardware by 2020, not that all cars counted will be able to use it (as obviously the select cities would only have a limited amount of vehicles, even if Tesla got the software ready in time0.
It's not that clear if the paraphrasing above is talking about autonomy day or some other private investor event. Admittedly I didn't dig through Autonomy day to find the direct quotes (I know to extremely careful with paraphrasing as journalists tend to get thing horribly wrong when they do that).