com.nomagic.magicdraw.uml.symbols.SymbolDrawNotification notifies when the presentation element is drawn (added to a diagram):

    // An element removal listener
    final PropertyChangeListener removeListener = new PropertyChangeListener()
    {
        public void propertyChange(PropertyChangeEvent evt)
        { 
            if (ExtendedPropertyNames.REMOVE.equals(evt.getPropertyName()))
            {
                // symbol removed
            }
        }
    };
 
    // An element drawing listener
    SymbolDrawListener symbolDrawListener = new SymbolDrawListener()
    {
        public void symbolAdded(DiagramPresentationElement diagram, PresentationElement symbol, String actionID)
        {
            // A symbol added
            // A register listener
            symbol.addPropertyChangeListener(removeListener);
        }
    };
    
    // A register draw listener
    SymbolDrawNotification symbolDrawNotification =SymbolDrawNotification.getSymbolDrawNotification(project);
    symbolDrawNotification.addSymbolDrawListener(symbolDrawListener);