Are you ordering from Alibaba? If so I would advise using a third party checking service to ensure your goods adhere to your contract - and if you agree on trade assurance terms then your more likely to be favoured if you have a inspection (should anything go against your expectations).
What Incoterms have you agreed with your manufacturer? Have they agreed Duty Delivered Paid (DDP)? Many suppliers say they will do this - but won’t provide you with the Duty, VAT or Import tax receipts. This is important so you can save on your VAT, if you want to register or obliged too.
Just some other future tips;
Also, try to register your brand as soon as possible - its very easy and not overly expensive for a few classes, and for the benefit; Amazon EBC is pretty much key to surpass your competition.
Adverts are what make products sell - so I advise that you test some different ad tactics, researching your top keywords etc, and if you have a registered brand you access to Amazon brand analytics which I find tremendously helpful - its more reliable than your Helium or Jungle Scout software.
You will likely spend a lot on adverts - and it will eat your profit significantly, until you can establish a good advert regime.
Also - you will be paying VAT (20%) on your Amazon fee’s and Advertising fees unless VAT registered.