Late february or early March.
Tournaments likely start using it in April.

Hello! I actually have some information on this

>Trailer sometime next week
>Shows the 3 battle modes again and the new spectator mode
>Battle Camera returns
>Recruiting is explained again and it is mentioned that during certain formats some Pokemon can only be rented but not recruited
>Longer segment for trainer customization (and monetization)
>A Battle Tower like mode is shown. It has events and special rewards
>Releases a week later on January 29, with a HOME update coming a day before
>Theres a starter pack for 39.99