I try to only if I know I'm going to get crap for it. I postponed telling my parents they were going to be grandparents up until last week. 馃槦My dad slapped me once for 'being stupid' and is still pretty angry, to the point he's offering me $3000 to get married right now.
But if it's something not as crazy but still touchy, depending on the person I'll mention it right away.