Fortunately, the Google Maps app lets you start the navigation mode a lot faster. "Select a place, then tap and hold on the transportation icon. This will automatically open voice guided turn-by-turn GPS navigation and you'll be ready to go," informs Google.
It's not an obvious feature, but it lets you skip 2 screens. You first had to pick a route, see the list of directions and then tap "Start".
This tip also works in the Google Maps app for iPhone and iPad, so it's not limited to Android.