Google Now provides a Commute Share option, so you can share your location with other users (private or public). In order to active this, you must tap the Menu icon, then tap Settings>Accounts & Privacy and turn on the ‘Commute sharing’ option. Next you can choose who can view your location from your Google+ contacts.
This will then allow the selected users to view a card showing if you have set off from work and how far away you are! From your interface, when you set of for home, the Traffic card will indicate the option is turned on. However, you can see a card of your friends/colleagues if they do the above process on their phones.