The ‘terminal-notifier’ entry in System Preferences -> Notifications only shows up after the first notification by Joplin is given, not before, maybe that is the problem gobblepotato is having. Make a todo-entry and set a time on it, and you will get a notification, and the ‘terminal-notifier’ will be there in System Preferences -> Notifications. ‘terminal-notifier’ is a very confusing name though!