Startups - How to Validate a Startup Idea?

There are two versions of this idea. One is we bring the chef to your apartment and they'll do a dinner party. The other is a dark kitchen, I don't know if that's in some places. You can run lean testing here and see if people like the idea but it's going to be a while before you have repeat purchase from that consumer. And then so will the word of mouth spread virally? It's getting much more complicated.