Historically, Microsoft publicly announces the next version of SQL Server about a year before it ships. For example:
November 2, 2021, Microsoft announced the private preview of SQL Server 2022. About 6 months later, on May 24, 2022, they announced the public preview. About 12 months after the private preview announcement, on November 16, 2022, SQL Server 2022 was generally available.
This was pretty consistent with past releases: about a year before the release, Microsoft would go on record with the features included with the next version, and some companies would be able to start using it in