I found this on the Apple discussion forums... (link:
https://discussions.apple.com/thread/3376201?start=0&tstart=0)
Some have suggested backing up the iPhone/iPad and then restoring it. Not sure the first day of the week should be Monday, so it's possible that the phone is wrong... Clearly there is no setting to customize the first day of the week. With Google Calendar involved, is it possible that the calendar was originally set up on a device that had that option?
I did not read all the way through that thread (it's 3 pages)...
It seems to be connected to the Region Format settings. When set to Australia they've changed it to start the week on a Sunday. As a short term fix until they change it back to Monday I've changed my region format to Barbados.
This changes the calendar to start the week on Monday, but keeps all other settings the same as Aus, even using google.com.au and doesn't seem to affect contact detail formatting either.
I'm not sure if this is a widespread problem, but I've submitted a bug report at Apple - Feedback. Hopefully they'll change it soon!
---------- Post Merged at 07:22 PM ---------- Previous Post was at 07:19 PM ----------
Also, I just checked in iCloud.com, and there is a preference setting in the calendar widget for first day of the week... could you switch to iClould (from Google Calendar) and see how it works?