Japanese dataminer tweet :
As expected, the fastest patch will be next Monday or after the end of the overseas WCS finals on April 3rd. The reason is as follows (1) Due to Zacian's ban in overseas WCS, the possibility of this week is low. (2) Zacian's implementation ends one month later, Zacian shop sales start next week. (3) There was an adjustment on March 28th (Monday) last year.
https://twitter.com/Cra_PokeUnite/status/1638692106368856064?t=WJ9ckTJRP_BcxgBQ6J3QDQ&s=19