Parents, I met my dh's by accident when I was out for a meal with him, he was separated not that long and still living in marital home. That was awkward and too soon.
Next meeting when he was looking at house and they just turned up, luckily all agreed he should buy the house. Then I think they invited me to dinner. That was 3 months in and was the right time. Knew it was more than a fling but might have just been on the rebound.
So parents less problematic, it's nice for them to know you are dating.
His kids I met too soon, but kept at quite a distance which worked. Didn't and haven't ever thrown self into SM role. Might be different if you both have kids.