Which companies? The earliest claim of an exploit attempt in the wild I had heard was October 17th, and that was “extant”, not “rampant”.
I don’t suppose you’re thinking of when the issue was discovered? That was August 1st, according to https://calif.io/php2shell/#the-discovery.
Amazon said 4 days prior to patch, but I'm pretty sure the other one was cloudflare, I can't find the link in my browser history.