You'll probably need to get more people in on it if you want it to be in a dictionary, but "enough" is really just the people you talk to.

Lots of families and friend groups have their own words, usually powered by inside jokes. Sometimes those words get picked up and spread around the neighborhood or even the town, and sometimes they manage to enter popular culture, thus slang is born.

So enough might just be your nephew, or enough might be everyone who's ever posted a dog picture.

for you, it's enough; for a dictionary, that's their decision. dictionary is not a law book. it's not a religious book either. it is not ordained by god. it's just a report of what words the speakers of a language use. which words are included or not are arbitrary and editorial decisions. what do you think makes the "cut" in a small pocket dictionary with 2000 words vs a bigger dictionary with 10,000 words? do you think once you publish the pocket dictionary, 8000 words stop being legit?

If you were a writer on a hit TV show. Yes.

Going commando existed in the 70's but only entered the public lexicon because of Joey.

You're conflating two topics.

1. How many people using a word in an existing language makes that word a word from a descriptivist context?
2. How many people does it take to make a conlang?

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.)

Only when it was coined. It's very cromulent now, and could be argued to have become cromulent as soon as the meta argument was understood: that good words are those that successfully convey meaning.