Oh, that's good to know because cfp.nixcon.org says 15:00 but without timezone, so I assumed it was 15:00 in my timezone!
Yes, blame me for this one. I didn't have things ready quickly enough to fix certain important user experience aspects like "showing the timezone".... which is kind of a basic and critical need.
Anyways, the widget at https://2020.nixcon.org/#program localizes to your timezone (but also shows weird dates sometimes).
Times from the cfp subdomain are all in UTC.
I'll be speaking how about how to get Nix to become mainstream.