Finalize the Dismiss Initial View and Replace Page setup

My Firebase login has the necessary dismiss initial view function to open one target “profile” page (with or without params). Despite previous help and research, I still don’t get how it works.
What does “dismiss initial view” mean?

After login,
if user is new, profile page loads with empty input fields (appVar “newUser”=true)
if user is not new, profile page loads with ID param and user info (appVar "newUser=false)
What else do I need here?

And here?

Original setup was correct all this time but a delay was necessary to give time to the Firebase login flow to find out whether user is new or existing and set a variable. Otherwise this flow fires too fast with empty page parameter.