flutter make get request before displaying app

I have a pretty simple problem. I have a code snippet that looks like this:

class home_page extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => Main();
}

class Main extends State<home_page> {
 void initState() {
    super.initState();
  }
 @override
  Widget build(BuildContext context) {
    Size size = MediaQuery.of(context).size;
    double height = MediaQuery.of(context).viewPadding.top;
    return Text('hello')
  }
}

I want to call a function that makes a get request to a local server, lets say ‘localhost:3000/getsomething’ and then after a response is gotten, I want to process that response, and then assign it to a variable. Then after that process is complete, I want to load the app. In the meantime, I want to show a loading icon that takes up the entire screen.

Here is a visual:

class home_page extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => Main();
}

class Main extends State<home_page> {
 var response;
 void initState() {
    loadData();
    super.initState();
  }

  void loadData() async {
    await //GET REQUEST
    response = //GET REQUEST RESPONSE
    //SHOW THE ACTUAL APP AND GET RID OF THE LOADING ICON
  }
 @override
  Widget build(BuildContext context) {
    Size size = MediaQuery.of(context).size;
    double height = MediaQuery.of(context).viewPadding.top;
    return Text('hello')
  }
}

Thank you so much!