Perhaps a good metric would be to ask this question regarding the Nexus 7 2013 wifi and Lollipop OTA:
What is the most recent date for an OTA upgrade of your Nexus 7 2013 WIFI? I know that many have received it, but would like to know when the last reported upgrade using ONLY OTA (not side-loaded OTA).
I'm in the US. When KitKat rolled out, I had mine within a few days (all variants of KitKat). Now, it's been about 3 weeks, and not a twitch (in spite of wearing down the tip of my index finger pounding the check update button) on my stock Nexus 7 WIFI 2013.