The answer to the second is, of course, one, but that’s a very different question than the first one. The first question doesn’t have a definitive answer. The more people that use some new word the stronger the claim is that it is in fact a word is, but there’s never a moment when you can definitively say everyone agrees that it is a new word. (If you could then we wouldn’t need to ask the question at all lol.)
Some N greater than zero, though probably at least two unless you’re inventing a language/dialect on your own.
*Tolkien enters the chat.
And that guy who fleshed out Klingon.
You’re conflating two topics.
The answer to the second is, of course, one, but that’s a very different question than the first one. The first question doesn’t have a definitive answer. The more people that use some new word the stronger the claim is that it is in fact a word is, but there’s never a moment when you can definitively say everyone agrees that it is a new word. (If you could then we wouldn’t need to ask the question at all lol.)