systemd locale

Timezone

$ sudo timedatectl list-timezones
...
Europe/Copenhagen
...

$ sudo timedatectl set-timezone Europe/Copenhagen

NTP

$ sudo systemctl start  systemd-timesyncd.service
$ sudo systemctl enable systemd-timesyncd.service
$ sudo timedatectl set-ntp true

Locale & 24 hour clock

$ sudo localectl set-locale en_US.UTF-8
$ sudo localectl set-locale LC_TIME=C.UTF-8