For me it may be this review of an album released in 1998 by Wrapped in Wire magazine: https://www.wrappedinwire.com/V/Vojna.htm.
For this exercise, should Usenet on Google Groups qualify? That's difficult to say. It's "living" because you can still reply to it, but these messages are no longer part of the living Usenet. Here is a reply I wrote on Aug 9, 1998: https://groups.google.com/d/msg/rec.music.industrial/pseJluJPys4/dx5fvt8roXgJ.
If there is a legitimate timestamp for the link you share, that's even better.
Edit: OK, I've found a post on sci.math from 1993 to which you can apparently reply
Edit 2: OK:
Jul 1993: https://groups.google.com/d/msg/sci.math/VfqtjzqD5vk/_I2qHiT...
Jun 1993: https://groups.google.com/d/msg/sci.math/sM5obXgILLg/WSMskMV...
Apr 1993: https://groups.google.com/d/msg/sci.math/pDjjVvQiQts/umBn0h2...
As for information written by me that is publicly preserved somewhere, I have a feeling that is actually a considerable amount of time later, likely around 2001 or 2002 when I started posting on random paintball forums, ebaumsworld forums, xbox forums. I'd also uploaded some videos on Putfile by that time.
So I guess it's time to celebrate my 20 year internet anniversary soon :)
Someone named "Nathaniel Silver" replied, and I wonder if that's the political and sports forecaster or someone else of the same name.
https://groups.google.com/g/sci.math.num-analysis/c/2j8pg4NV...