Okay, I think I have an idea why I am getting oddities with the post-title times. I set my time offset to 0, and I get "Today at 2:27 AM" for my third post (#46), before it said "Today" even with a future hour. I'm pretty sure the prefixes aren't taking time-zone into account.
To compare, my earlier post (#39) is posted "Today at 11:24 AM", and edited "Yesterday at 11:34:14 AM" when the time offset is 13.
With the offset at 0, it's posted "Yesterday at 10:24 PM" and edited "Yesterday at 10:34:14 PM".