Self employed start up advice please

[Numero4]

I'm starting up my own business, I design items and have them made abroad. I've got a few items so far but will be waiting months until I get the whole collection. I've built a website, Facebook and social media pages where I've put photos of the few items I have at the moment and just getting to grips with how the website works, practicing insstagram reels etc. Question is, I won't be actively marketing or promotion anything until I get my full range so when do I tell hmrc the business started from, seeing as it will be unlikely have any sales until I've start promoting myself and I haven't started yet as such? What if I get all my range and get no sales, do I then still have a business to register? New to all of this and tried looking online. I was told I don't have to pay tax for the first 18 months. Is this correct?

What kind of entity do you want to run, so Ltd company, sole trader etc?

How are you importing these goods ie in your company name or in your personal name?
Do you need to be VAT registered, do you need an EORI number?

I ran my own business for many years, I had things manufactured in differing countries, I started as a sole trader and then registered my business as a Ltd company. I think I did my own tax return after I had actually made sales when I was a sole trader (I didn't need to be VAT registered then).

So I'm going to be a sole trader for this business. I'm already a partner in another unrelated business.

I'm importing them in my company name. I will need an EROI number, I'd looked into this a while ago but completely forgotten about it!
I won't need to be vat registered, at the moment it's just a small side business but it would be lovely if I was making that much one day.

So I should probably send in a tax return next January? I bought some things before March this year, I assume I can't include them?

Thank you for the reply.