Event after camera loading?

Hi,

I'd like to show a loading screen untill the camera has fully loaded (so after the black screen). I am aware that I can subscribe to ARSubsystemManager.cameraFrameReceived, but this will still include the black screen delay on camera startup.
I could add an event to when the camera is done loading and fading from black to camera view, but I can not find where this happens.
Does anyone else have an idea? I don't want to have to implement a dirty fix for this in the form of a 2 second delay after ARSubsystemManager.cameraFrameReceived fires.