how to initialize?

[nohkumado]

Hello!
i like the preference screen i can make with this, but am stuck with an annoying problem....
my main dart starts with :

 SharedPreferences prefs = await SharedPreferences.getInstance();
   WidgetsFlutterBinding.ensureInitialized();
....

but on my welcome screen where i display a setting:

Widget build(BuildContext context) {
Settings().getString( 'key-filename', 'none' ).then((value) {
			print("retrieved filename : $fname");
			fname= value!;
		});

on start returns "none" i need to explicitely go to the settings screen and return back to the home screen to have this filled correctly??

what am i doing wrong here?