I'm in Europe (United Kingdom, not mainland Europe) and I've never heard anyone say 19 o'clock, that doesn't mean it doesn't happen, I've just never heard it and I'd find it quite strange if I did.
Schedules are usually made of context: Shall we grab a drink at eight? (Nobody drinks at eight in the morning, so it must mean the evening.) – Shall we have a meeting at two? (I'm usually asleep at two in the morning, so it must mean the afternoon.) – it's rare that I experience ambiguity in times.
Schedules are usually made of context: Shall we grab a drink at eight? (Nobody drinks at eight in the morning, so it must mean the evening.) – Shall we have a meeting at two? (I'm usually asleep at two in the morning, so it must mean the afternoon.) – it's rare that I experience ambiguity in times.