For this one startup time trials from the main page. This will give you 8 minutes to finish a mission. Use a car to get you to the closest train station or helicopter pad. You may need in-game credits to buy tickets for these so beware before trying. I took the train to the bottom left area on the map as a helicopter pad is really close and easy to get to down there. It would work the same if you used the chopper to get down to that area as well. My achievement popped in route to the next location.