What do I complete first ?

I have a product that has a pending trademark . What are the proper steps ? Do I sign up for Brand Registry first or just list my product to see if it gets approved ? My thought is to show legitimacy is to complete the Brand Registry first . This will be the only product I’m selling at his time ? Any advice is welcome. Also, is it advantageous to have an Amazon approved company help my listing process? Much thanks 🙂