The update finally happened for me in the UK sometime between midnight and 8.00 am on Friday 13 October (Android phone Samsung Galaxy A13). I have app auto updates turned on, so if you have them turned off you'll need to look up the app on Google Play Store.
I looked up the instructions for calibration on the
Dexcom site and, as so often seems to happen to me, they are different to what my phone shows. I don't have a 'Glucose or History' tab, just 'Glucose', 'Reports' and 'Settings' tabs, and the new calibration stuff is under 'Settings'. There is also no glucose recording, although the Dexcom site suggests there is.
So I've tried a calibration as my Dexcom one gave me a low warning at 4.4 (set to 4.5 on consultants advice) as I was writing this. My finger stick test told me I was 5.5, and the Dexcom gave me the next reading as 5.2. I only have 2 days left on my sensor, so maybe it will uncalibrate when I fit a new one.