I want to downsize a Linode from the 16384 plan to the 8192 plan. According to the Resize tab in my dashboard, this is estimated to take approximately 288 minutes. Is that number generally accurate?

Assuming both Linodes are in the Newark datacenter, what would be the best time of day to attempt the resize?

Since you are resizing down, you'll first need to resize your disk image smaller. That will cut down on the migration time quite considerably. Also, we're pretty conservative on our migration-time estimates. They have improved quite considerably with the recent upgrades.

-Chris