Decided to check up some dates to make sure and, guys, if patterns are to be believed, and if Nintendo, Sakurai and Co. are going along with it;
- The first Fighters Pass was announced during the 11/1/2018 Smash Direct (yet no release date).
- Challenger Pack 1 - Joker from Persona 5 was revealed during The Game Awards 2018 (first DLC fighter of the pass; this took place on 12/7/2018).
- The first Fighters Pass became available for purchase on... 12/7/2018.
- On the latest Smash Direct (from 1/16/2020), Sakurai officially announced Fighters Pass Vol. 2, which will consist of six (6) Challenger Packs. The Pass will be available for "pre-purchase" (actually, just purchase because it'll be just as last time with the first Fighters Pass) on January 28th, 2020.
- Following from 2018's timeline then, Challenger Pack 6 (the first DLC fighter of the second pass) could most likely be revealed on... January 28th, 2020.
Going a bit further with the aforementioned points, if the pattern is to mirror that of 2018's not just on timing, but also on impact, I could in fact see Challenger Pack 6 being Crash Bandicoot since, right now his situation feels similar to Hero's. I say Hero's because back then, prior to E3 2019, Erdrick had been rumored and mentioned around A LOT, and apparently it was known that he'd be coming around that time (correct me if I'm wrong). Likewise was Banjo's case. Besides the noise surrounding Crash, it has a parallel to Joker in that both characters come from Playstation exclusive games (although Joker appeared on Persona Q2 for the 3DS); except that in Crash's case, this is true ONLY in retrospect (the late 90s era). Both are characters that at first glance are seen as "Playstation exclusive" but, with the passage of time their games have made their way onto Nintendo systems (Crash of course appearing as early as the Game Cube era).
As for Geno, I guess I'll bank from now that he'll most likely be an E3 2020 reveal a-la Banjo & Kazooie (following the consensus of some Genobros of him being one of the "never-evers"), being revealed near the end of the Direct.