When looking up directions on the web, click the Leave now button, then Depart at to tell Google Maps when you're planning to start your trip. Set your time and date, and you'll get a more realistic estimate of your traveling time. If you want to make your life even easier, you can choose an arrival time and Google Maps will tell you exactly when you'll need to leave. Simply look for a place, then tap Depart at, and Arrive by on the first navigation screen. You'll be able to set a specific time and date, and the app will adjust route recommendations according to traffic. You can find the same options on the directions screen by tapping Depart By > Arrive at.