The update is a few hundred megabytes, and the OTA updates take a while to roll out to all devices (~weeks/~months).
Chances are you will be fine, but Branch Delay said he will put together an easier method soon, so I will leave him to that.
It would presumably involve an easy way to temporarily cut off all internet access and/or reroute it all to the webserver.
For general reference, the Block Big Brother firewall (KUAL hack) has a list of useful IP addresses to block out just Amazon:
https://www.mobileread.com/forums/sho....php?p=2425330