I have not seen the piece of paper before, but by the end of January I think the word was already getting out.
In December 2019, some time before the Chinese government publicised the fact that there was a novel pneumonia, Dr Li Wenliang was speaking out about the virus, and for some reason was arrested and reprimanded. Li Wenliang later died of the virus in early February.
Another Doctor in China who was punished for blowing the whistle that the earlier 2003 SARS virus outbreak, was being played down dangerously by the Chinese authorities, died of pneumonia in 2023.
There is a VERY strong tendency for the Chinese to suppress bad news like this, especially if it could ever be thought to reflect badly on the government, whose reputation must it seems, be always massaged to make them look omnipotent.
The last thing that matters to the government there is that public health is protected before the reputation of the Chinese Communist Party.

Jiang Yanyong: Whistleblower doctor who exposed China's Sars cover-up dies
Jiang Yanyong became a national hero after revealing Beijing was covering up the scale of the virus.
www.bbc.co.uk
The cover up mentality is so strong that the way they suppressed information about the lab leak idea can not be trusted. There has been no open investigation into where sars-Covi-2 came from and there is a mountain of circumstantial evidence that it was not a natural event.
I note that Doctor Nigel has not in ANY WAY engaged with the points I make about why Sars-Covi-2 is unlikely to be a natural spill over. He prefers to pick cherries I am afraid.