Did you write a business plan?

I hate the strict formalities of a business plan. That said, it makes sense to think about the things you usually put in there.

To answer your question: No, I didn’t write one but I have a bunch of Notion pages which essentially contain the same info.

Most people don't. If it's one of your first businesses you should probably consider it, though. If you're seeking outside investors / partners it's a must.