That 16 is the day, not the year.
The first post is listed for me as being posted at
Aug 16, 2018 1:20am (hover over the ‘15d’ with your mouse and you get a tooltip stating the exact time and date).
I don’t know if that’s UTC or my local time, but if that’s my local time I’m currently UTC+1, so it would still be the 16th of August in UTC.
The timeline of this this thread says
And upon posting this, I’ve discovered that the tooltip time is local time, so it’s possible the timeline time is UTC time or something if you’re getting a tooltip time of Aug 15 for the afforementioned thread.