ELI5 – Create Amazon Seller Central Account or Enroll Brand Registry First?

Hello! I’m not new to e-commerce (I’ve sold on Shopify before) however I am very new to selling on Amazon. I have my brand, products and I’m ready to sell on Amazon, however, I’m confused as to if I should sign up for an Amazon Seller Central account first? Or enroll my brand in Brand Registry? Which step first, then how do I connect them? I just want to make sure I do this process correctly so I can avoid any future headaches. All insight is appreciated.