Hey there Adsie,
I apologize for the late response, thank you for being patient! The updates should be released everywhere by now. Here is how to manually check for updates to your Chromecast:
If you have a Chromecast with Google TV, the update doesn't appear in the Google Home app. You need to access your Chromecast updates from your TV. To do this on your Chromecast with Google TV home screen, choose Settings and then System and then About and then System update.
I hope that helps, and if you have any other questions or concerns for me, please let me know.