Just a simple (hopefully not blasphemic) question: why don’t you have the TV turn on automatically on CEC ?
You should be able to configure Kodi to send CEC on (Kodi) UI interaction or similar (I think it does anyway).
I’ve got a similar setup, just I have another media player (Dreambox TV receiver) to send CEC when you turn it on, so that’s how I start my combo.
No other chance anyway since I’ve got one of those new Samsung TVs that aren’t supported by the binding yet.