https://www.businessinsider.com/el-paso-shooting-8chan-posts-gamification-of-mass-violence-2019-8

Looking to an archived copy of the 8chan post, we can see that the post was made at the Unix time of 1564848920, which converts to August 3, 2019 at 4:15pm (UTC) — or, in local El Paso time (UTC-6), 10:15am, just before the first reports surfaced of a shooting in El Paso.

While all of this could technically be an extremely elaborate hoax, it would require the poster to know the suspect's name well ahead of time. Additionally, there is the fact that the post was made before any public reports of a shooting, and even longer before the name of the suspected shooter was released to the public, and included information that matched the attack ( model of weapon, targeting a heavily-Hispanic area).

As we've seen with two other mass shootings this year, the killer announced the start of his rampage on 8chan's /pol board. The poster also attached a four-page manifesto to the post, along with a document in his original post that included his name — Patrick Crusius.

This original 8chan thread was deleted almost immediately by site moderators, who by now have gotten quite experienced at pulling mass shooting threads from their website. The archived version of the post has only three responses. The first is an anon claiming that 8chan is a "board of peace" which does not condone violence. This phrasing is a meme among the anons; a mocking reference to statements that Islam is a "religion of peace". The next poster after that said simply, "Every shabbat", expressing his hope that mass shootings like this happen every weekend.