We started out not out much at all, but the more involved we got with the poly community here, the more were were out everywhere. Not to everyone, of course. But if you didn't know me well enough to know my wife's name or that I even had a wife, then you weren't likely to know about other partners. But in general, if you knew us, you knew we were poly.
When I was living with both my wife and boyfriend, we didn't usually go to any trouble to out ourselves. We just were. We showed up as a unit, and if you had questions, you could ask. Most people just accepted it.
This was also back when we were raising a child and had corporate jobs. I don't think we ever felt like we were risking that much. Mostly people were curious or envious, not scandalized.
Family was another issue. They all seemed to be fine with our coming out, but later didn't act very accepting at all. My sister threw a hissy fit about only inviting only one of my partners to her wedding. Neither were likely to come in any case, but it still irked me, especially as she has had her fair share of non-traditional relationships. My wife's aunt spitefully outed us to another family member, when we all bumped into each other in a public place where we were attending a poly meet-up. My in-laws made a big deal before our wedding that basically amounted to, "now that you're getting married, you'll stop all that silly poly nonsense."
That said, now that we haven't been actively poly in a few years, we're not out to many people at all. We have loads of new friends, and the topic never comes up. I don't think most of them would mind or judge us if it did. And sometimes I don't even think to out ourselves, even when there is an opening. For example, we were invited to a friend's house for dinner with another couple, and when I asked the wife how she met our mutual friend, the answer was "Oh, I'm dating his brother." I said cool and we chatted about it, but it never seemed like a good time to slip in, "oh hey, we used to do that sort of thing, too."
Sometimes it feels very strange to reflect that so many people in our lives now don't know what seems like a very basic fact about us. Most of them also assume I am a lesbian, because the topic of my exes (all men) has never come up. As we move back into being actively poly, it's obviously something we'll have to figure out all over again.
As a secondary, if you were hiding me all of the time to everyone, that would be too much for me to deal with. I won't out you, but I probably wouldn't stick around long. If it's just specific people or situations, however, I don't mind being respectful of that and letting you do what you feel you need to do. But yes, please let me know where those lines are early on.