Everyone has a different approach to design and it is our aim with Codesign to support multiple workflows.
If you like to sketch first then this is the workflow for you!
You may for example like to draw bubble diagrams to explore different layouts and concepts. You may explore many iterations before you are ready to begin massing your building.
Once you are ready, use the Send sketch to 2d View in the Share menu:
Once you go back to the Primary view you'll see your sketch has been placed in the center of the working area.
You can now use the Image Scale tool to set this roughly to the correct scale and then begin to create your design tracing over the top of the sketch.