The press release announcing the ATEM Mini indicated that it would start shipping in November 2019:
https://www.blackmagicdesign.com/media/ ... 0190913-01Usually these dates indicate the time that Blackmagic intends to start shipping the products to retailers, so it's often a week or two after this that the products end up in the hands of actual end users. So even if they hit their target and start shipping to vendors by the end of the month it would likely be early December before users receive them.
There were 3 products announced at IBC in September, the ATEM Mini, Video Assist 12G HDR, and new Videohub Control Panels. As far as I know, none of these products has started shipping yet, so it's possible the ATEM Mini could be delayed as well.