I would say that Once Madara summoned the Gedo Mazou, Spiral Zetsu was created. I think Old Madara used Spiral Zetsu as a power suit to bypass his old age. Yes, Spiral Zetsu enhances Physical capabilities of the wearer. The mask of Spiral Zetsu would have also hidden Madara's identity. So essentially, I think Tobi was born of Madara using Spiral Zetsu as a mask. Later on, Obito, Madara's successor replaces Madara.
Spiral Zetsu was born from the Gedo Mazou but there is no solid evidence that he was born a few days before Obito was crushed and retrieved by Madara. The manga evidence hints that Spiral Zetsu was formed a few months after Madara summoned the Gedo Mazou with his Rinnegan.
He used Spiral Zetsu as a suit and when Spiral Zetsu ran out of Energy, Madara would re-attach Spiral Zetsu to the Gedo Mazou.
What further reinforces this is that Spiral Zetsu's insides were carved out to form Obito's Right Zetsu half. And Madara was able to easily control it with his will. This implies that Spiral Zetsu was also implanted with Madara's will.
Spiral Zetsu was born from the Gedo Mazou but there is no solid evidence that he was born a few days before Obito was crushed and retrieved by Madara. The manga evidence hints that Spiral Zetsu was formed a few months after Madara summoned the Gedo Mazou with his Rinnegan.
He used Spiral Zetsu as a suit and when Spiral Zetsu ran out of Energy, Madara would re-attach Spiral Zetsu to the Gedo Mazou.
What further reinforces this is that Spiral Zetsu's insides were carved out to form Obito's Right Zetsu half. And Madara was able to easily control it with his will. This implies that Spiral Zetsu was also implanted with Madara's will.
