Inside Cinema 4D 2024.1.0 it is now possible to choose the default start-up scene.
This way, you now can define your own startup scene and easily switch to a blank scene as well.
Under Edit > Preference > Files.
You can choose;
Blank - Starts with a standard blank scene file.
Logo - Starts with the Cinema 4D Logo Start-Up file.
Custom - Starts with a user setup custom scene file.