My advice to everyone: just don't talk about it. Write in secret, and surprise them when you've got a contract. Yes, I know it's hard, but to my mind it;s important.
When I wrote my very first novel, I let everyone know. I even discussed the story with some friends. Now, most people have no idea about the publishing process and in a very short while I was getting questions like "When is it coming out?"
I hated it; especially as this novel was years in the rewriting, and people who imagined it would be published in abot six months just assumed I was a loser.
That book never did find a publisher, but I learned a lot from it. The next book, I wrote completely in secret. The only people who knew I was writing at all were my immediate family,and even they didn't know WHAT I was writing, until I got an offer of a contract. Mind you, I still got annoying questions. I was a stay at home mom at the time, and ex-colleagues of mine - one woman in particular - kept insinuating that I was letting myself go rusty, I should get back to work (NO WAY!) to keep my self respect, how boring my life must be and so on. It was very difficult keeping the secret: that I was having the most amazing adventures - in creating fiction, and life had never been so interesting, and that it was the DAYJOB that was deadening!
AFter that it was a bit simpler as I had contracts for the next two books before they were written; but the "what's it about?" really gets on my nerves. According to Dorothea Brande, who wrote my Bible of writing, Becoming a Writer, you should NEVER tell anyone the story of your book, because then the subconscious mind thinks it's been told already and shuts down.
For my fourth novel, for which I did NOT have a contract, I made the mistake again of telling friends. Again the questions: "How's it going?" "Found a new publisher yet?" "What's it about?" Grrr!