I\'m having trouble understanding when access to the shadowRoot of a component is available. Here is an image of a set of nested components:
I find your description difficult to understand but usually in attached after the super.attached(); call all things are proper initialized.
If you can provide the minimal code that allows to reproduce your problem it would be easier to make concrete suggestions.
In core-elements (JavaScripts) ready() callback is used most of the time instead of attached. I haven't investigated which one is called earlier/later because attached (was enteredView) never failed me.