I Technically came out to my parents as going through the questioning phase. a while back Do you think questioning is a good time to come out?
I think it might depend a lot on how your parents are to be honest. If they're likely accepting, then I'm sure they're capable of understanding it's no easy process and nothing is set in stone. Though if they aren't going to be accepting or they'd be a "tough sell", then I think it might be better to be more sure before you make any announcements.
If you know your parents are not going to be accepting, coming out as questioning gives them 'ammo' in the sense that they can go: see you're not sure, it's probably just a phase/in your head.
No, I was questioning and came out to most people. Now I'm not so sure but my friends just see me as at least bi, rather than 'questioning'.
I, honestly, think it is best to wait to come out to family until you know for sure what your orientation is. It is often times hard for them to wrap their minds around "questioning" and that leads them to believe that they can change you.
It could indeed lead to them to think even more that they can influence your sexuality, or be like, 'questioning? I'll give you an answer, you're straight and that's that!' in the worst case. But like others have said, it depends on how your parents view sexuality. Even if I knew my parents were accepting I wouldn't've told them I was questioning. Even if I sort of am. I've just told them I am bisexual (they're hoping I'm straight now or something, seeing as I broke up with my first boyfriend, ugh). To friends it's different though, it would make them feel even more trusted I think, if you tell them you're not sure. Plus, it'll be helpful to yourself. Just talking about it and stuff.
When I came out as questioning my mother came out as bisexual to me and my dad admitted he was transgender. You'll be surprised what you don't know about your folks.