Interesting...when I pre-purchased AC on my MBA earlier this year, I asked Apple about the start date for AC as it was activated from the day it ships – they told me it would expire/renew on that date, not when I actually receive/activate the device. Checking the renewal date in System Settings, it’s the same as the Proof of Coverage email I received – I received the MBA about a week after that...so it hasn’t been adjusted.That’s not strictly true. Yes initially the Apple Care starts from the day you preordered or ordered but it’s always adjusted to the day you set up and start using your device.
I preordered my phone on the 15th and it was delivered on the 22nd so initially my Apple Care started on the 22nd but I didn’t set up my iPhone until yesterday which was the 25th. I have the monthly theft and loss plan so mine now renews on October 26th.
Maybe it works differently with monthly or phones?