And you can get started now as some Summer/Fall 2020 shells can be found if you search in Courses. Remember that Fall 2019 BB content was not moved over but Fall 2018 BB content was. Summer 2019 content was migrated to Canvas. If you do not see your 2020 course you can still start working on building it in one of your Sandbox courses and then copy to the 2020 course when available.
Instructions for importing BB content to Canvas can be found here