For everyone, who wants to start with different screen than Home:
I tested and use this add-on very well:
Pure. Simple. And take small space enough.
Just download zip file, install add-on from zip, and select which screen you want on startup.
service.autostart.library-master
https://github.com/Steveb1968/service.autostart.library
(There is large fanart image for using with your startup screen, you can just remove this file from zip before you copy zip file to OSMC. Without this image, it takes only 160kB of space.).