I've read a lot of discussions regarding when to share your manuscript. My answer is that I never let anyone read it until it's done. Then a few beta readers get to see it. I think an unfinished story is like an unfinished painting. You can't really see what it will look like when it's in its early stages.
An even harder question to answer is what do you discuss when you are working on your WIP? Since I have asked a couple of friends to do read-throughs for me, people hear that I have written something. Then they want to discuss it. I always feel awkward and embarrassed. Now, I really love writing, and I know I shouldn't feel this way. But really, what do you say? When am unpublished, and I say "I wrote a book," I always feel like that random loser you see in old 80's movies, proclaiming that he wrote a move script that such and such actor just has to look at.
I've had three people ask me about my writing today.
1) Beta reader and friend- when is your book going to be in print? It needs to get published, now.
Answer: I have no freaking idea. Maybe when an agent shows interest. Maybe when pigs fly. Let me just trot right out and do that.
2) Beta reader's mother (also a really good friend)- So I hear you wrote a book. One with vampires. (As she eats Edward Cullen birthday cake).
Answer: I've written several books actually. Yeah. There's vampires. I'm glad you're excited. (The last beta reader said she was "crestfallen" to discover that the love object was a vampire. But my vampires don't sparkle, and I'm not a bandwagon jumper. I loved them before they were popular. )
3) My husband, A.K.A. real life man of my dreams (RLMMD for short)- What's this one about?
Answer: I could tell you, but it will sound crazy. There just aren't words sometimes.
RLMMD: I get it. Like reading the description of a manga.
Answer: Brief description of my amazing story idea.
RLMMD: I'm just rolling with it. I mean, the rest of it sounds cool... but does there have to be vampires?
Answer: Fuck you.
We sign divorce papers tomorrow.
I think this is the problem with sharing your work. Talking about it is just awkward unless you are a published success. Otherwise you just sound like a weirdo. Also, the people who are likely to ask you about it in social settings have no clue what you are talking about. Then there's the risk that someone will shun your ideas, causing you to be hurt, and making your confidence falter. (Okay, I'm not usually that fragile, but RLMMD has super powers.)
So, from personal experience, I think a gag order is advisable until work is absolutely complete (and possibly until it's published) is really the best way to go, unless you are talking to other writers.