Hi Jack,
As I said previously, you're an EU citizen so you don't need to show €40,000 in the bank, but it won't do any harm. If you already have an NIE and own your own home, it will be very straightforward to obtain your Certificado de Registro. When you're ready to make the move permanently, just ask for gestor recommendations in your area and they can help you make the application.
Kind regards,
Kim