The release of the first ARM-powered MacBooks will apparently follow the trend of recent Apple hardware announcements. Instead of a physical event ala recent iPhone launches, the ARM-powered 12-inch MacBook and MacBook Pro 13 will land without notice at the end of October.
https://www.notebookcheck.net/Leaker-claims-that-Apple-may-not-have-a-Special-Event-planned-for-its-first-ARM-MacBooks.485179.0.html