I have seen most of the sellers make this mistake! Starting ads right after uploading their product on Amazon or any other ecommerce platform. BUT You should focus on getting those product listing's retail ready first which means getting their images up for better CTA, optimizing listing content, Adding EBC and having a user friendly storefront. Most important of all you should focus on pricing. You need to be competitive in every aspect to convince a customer to purchase a product from you. Simply Said - "It's a fish market but digital" - where every seller is trying to attract customers by all means. I'm not saying PPC is bad or pick this and forget the other - instead what I want to say is everything is there for a reason but you have to pick the right person who knows how to do it.