Do something on app start first time

public class MainActivity extends AppCompatActivity {

  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        SharedPreferences prefs = getSharedPreferences("prefs", MODE_PRIVATE);
        boolean firstStart = prefs.getBoolean("firstStart", true);

        if (firstStart) {
            //call any methods or functions to load at first
            timerDialog();
           // SharedPreferences prefs = getSharedPreferences("prefs", MODE_PRIVATE);
            SharedPreferences.Editor editor = prefs.edit();
            editor.putBoolean("firstStart", false);
            editor.apply();
        }
        
               
    }
             
        
 }