Commander Legends products were originally scheduled for a prerelease on October 30 with a full-retail release set for November 6 (see "’WotC Drops Deets on ‘Commander Legends’"). Recently, WotC moved the release of the Collector Boosters back to November 20 (see "Delays on Upcoming 'Magic: The Gathering' Releases"). Now, the entire line of products has been pushed back to November 20 with prereleases rescheduled for November 13.
WotC will follow up with more information about retailers rescheduling prerelease events on their EventLink in the coming weeks.
Check out ICv2's Magic: The Gathering Release Calendar for more information releases and production delays.