What? That must be a bavaria/switzerland/austria thing. I never heard this. hearing quarter ten (Viertel zehn?) i’d assume 10:15 and most definitly not 09:15 0.o I’ll stay with quarter before ten for (viertel vor zehn) 09:45 and quarter after ten (viertel nach zehn) for 10:15.
you talking out of experience? 😏