code: def initialize_plugin_in_mainwindow_layout(self):
          
          if self.get_option('first_time', True):
              try:
                  self.on_first_registration()
              except NotImplementedError:
                  return
              self.set_option('first_time', False)
docs: If this is the first time the plugin is shown, perform actions to
          initialize plugin position in Spyder's window layout.
  
          Use on_first_registration to define the actions to be run
          by your plugin