I would assume CST since it says so on the program 
I suggest trying to catch a few of the talks you are most interested in when they are live - and if you really want to you can do a screen capture (or take screenshots of slides) so you have some references until the video recordings + slide PDFs are released. Last year roscon was the 20th & 21st of October and the videos were available on the 10th of November (📹 ROSCon 2022 Videos and Slides now Available), so hopefully they are as fast this year 
Edit: See below - the program was wrong (I removed the image saying CST to avoid further confusion)