For me I think it was when it hit Italy, so early
March. Until then I really believed it'd be a storm in a tea cup like swine flu.
I remember certain songs I was listening to as I refreshed the news in early March that still give me the heebie jeebies even now.
And I remember taking my dog for a walk at some lakes a few miles away (so drove there) and wondering, on about the fifteenth of March, if it might be the last time for a while. When I was there an elderly man said to me that it was nice to get out to forget the state of the world, I'll always remember that.
I remember seeing the Wuhan hospital be built and only paying the vaguest amount of attention. So arrogant to think it wasn't a problem for us!