I'm definitely the over 50 crowd. It is just impolite not to respond to an invite. Either say yes or no! As for the start time, Crankin, I'm with you on this. My ex and I used to have blow outs cause when the invite says 8:00PM, I would want to show up at 8:00PM not 8:30PM, not 8:45PM or even 9:00PM. Then I learned that here in US it was typical for people to show up "fashionably late" by about 30 minutes. This drives me nuts!! It also drove my German friends nuts too.

Is it a cultural thing to be "fashionably late" (30minutes?)