Google's departure time (or 'Time to leave') notifications feature is completely broken. If you take a look at the company's official forum, a large number of users are reporting the functionality is not working for them.

The thread in question started back in November, and complainants are still coming in. Here's a comment posted a couple of days ago:

"I have the same issue. I have notifications turned on for Recommended departure times. I also have importance: Urgent (Make sound and pop up on scree) but nothing comes up for calendar events that has location information."

Some users have found a workaround, which involves the Chrome web browser - on your device, load the desktop calendar UI, and enable the "time to leave" notifications option. This way, Chrome will fire notifications for you (see example below).

Unsurprisingly, Android Wear users are also facing similar issues. In fact, the problem has been reported on Google's Issue Tracker website as well, with the company recently saying it's working to resolve the problem.