ive been doing some research
this was posted on 1/10/01:
https://www.newschoolers.com/ns/forums/readthread/thread_id/493
and in it they say it was 3 days after ns was created.
so therefore 1/7/01 is the earliest possible date for a thread.
https://www.newschoolers.com/ns/forums/readthread/thread_id/494
is the earliest one i have been able to find, the dates start increasing in both directions.
im sure someone that cares more than me would check all of the URL's up to 1000 and find it but this is pretty close