After installation you need enable and start timekpr.service:

sudo systemctl enable timekpr.service
sudo systemctl start timekpr.service

• If you whant to be able control timekpr-nExT without superuser privileges, add your account to the timekpr group:

sudo gpasswd -a $USER timekpr

and re-login to session.

• If you are using a GNOME Shell, please do not forget to install "AppIndicator and KStatusNotifierItem Support" GNOME extension manually for every controlled users, otherwise icon will be hidden!