public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(Controller.class.getResource("sample.fxml"));
        primaryStage.setTitle("First my game");
        primaryStage.setScene(new Scene(root, 640, 480));
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.GridPane?>

<AnchorPane fx:id="parent" prefHeight="480.0" prefWidth="640.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/2.2" fx:controller="com.w2d.scene.Controller" />

public class Controller {
    @FXML
    AnchorPane parent;

}

public class Utils {
    public static class Resource {
    // подгрузка ресурсов
    
    public static HashMap<String,Scene> scenes = new HashMap<>();
    
    public static void load() throws IOException
    {
        // подгружаем сцену после вызываем её через Utils
    }
    
  }
}

    public static void load() throws IOException
    {
        Parent rootSplash = FXMLLoader.load(Game.class.getResource("Splash.fxml"));
        Scene splash = new Scene(rootSplash);
        
        Parent rootMenu = FXMLLoader.load(Game.class.getResource("Menu.fxml"));
        Scene menu= new Scene(rootMenu );
        
        Parent rootGame = FXMLLoader.load(Game.class.getResource("Game.fxml"));
        Scene game = new Scene(rootGame);
        
        scenes.put("splash", splash);
        scenes.put("Menu",menu);
        scenes.put("game", game);
    }

...
Stage.setScene(Resource.scenes.get("game");
...

public class SplashController implements Initializable{
    // Splash.fxml
    @FXML
    private ImageView splash; // Наше изображение
    @FXML 
    private AnchorPane parent; // Наш контейнер
    // Вызывается при появление контейнера
    @Override
    public void initialize(URL location, ResourceBundle resources) {
    	// code
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" fx:id="parent" onMouseClicked="#click" prefHeight="480.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/2.2" fx:controller="game.SplashController">
  <children>
    <ImageView fx:id="splash" fitHeight="479.0" fitWidth="638.6666666666666" layoutX="1.0" layoutY="1.0" pickOnBounds="true" preserveRatio="true">
      <image>
        <Image url="@../resource/splash.png" />
      </image>
    </ImageView>
  </children>
</AnchorPane>

public class SplashController implements Initializable{
    
    @FXML
    private ImageView splash;
    @FXML
    private AnchorPane parent;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        Timer timer = new Timer();
        
        timer.schedule(new TimerTask() {
        @Override
        public void run() {
             Platform.runLater(new Runnable() {
                boolean isTimer = false;
                @Override
                public void run() {
                    if(!isTimer){
                        if(splash.getOpacity() < 0) {
                            isTimer = true;
                            timer.cancel();
                            Game.STAGE.setScene(Resource.scenes.get("main"));
                        }
                    splash.setOpacity(splash.getOpacity()-0.05);
                    }
                }
            });
        }
        }, 500,100);
        
    }
}