React Native & Expo, how to control the splash screen?

Question

I'm using the built in splash screen in expo that you add in app.json for a simple test app. However I noticed that my start screen flashes in default mode 1 millisecond before showing the assets that I've added with AsyncStorage.

I've tried using splash-screen package from expo but I found it a bit confusing. Is there a fairly easy way to add in my App.js this logic :

Show a splash screen and when all assets are loaded, load this setup (with my contexts and screens), or just increase loading time of the build in splash screen from expo (because I assume it loads over the assets being fetched?).

const App = () => {

  const [selectedTheme, setSelectedTheme] = useState(themes.light)

  const changeTheme = async () =>{
    try {
      const theme = await AsyncStorage.getItem("MyTheme")
      if (theme === "dark"){
      setSelectedTheme(themes.nightSky)} 
      else if (theme === "light") {
        setSelectedTheme(themes.arctic)
        }
    } catch (err) {alert(err)}
  }
  
  useEffect(()=> {
    changeTheme()
  },[])


  return (
    <ThemeContext.Provider value={{selectedTheme, changeTheme}}>
         <NavigationContainer>
            <Stack.Navigator screenOptions={{headerShown:false, presentation: 'modal'}}>
              <Stack.Screen name="Home" component={home}/>
            </Stack.Navigator>
          </NavigationContainer>
    </ThemeContext.Provider>

  );
};