This can be unlocked fairly early if both drivers get 1st and 2nd place spots each race for the Constructors Championship.
1) Find a partner
2) Start a coop championship
3) Set it to 3 laps and one shot qualifying
4) Adjust the difficulty to these settings:
4a) AI Skill: Amateur
4b) Rules and Flags: OFF
4c) Car Damage: OFF
4d) Everything else is up to you
5) Select your team to be with Mercedes to avoid the two best racers in the game and have the best car
6) Invite your partner and get to work!
You both should unlock the achievement once you get the points needed for the Championship.
Except for Monaco and Singapore, I would suggest skipping qualifying (in the pause menu, go to Session Options and chose to retire) to save some time. Since there are no rules and damage, you can illegally overtake everyone at the beginning of each race.
Monaco and Singapore are the toughest tracks in the game, getting pole position through qualifying is definitely recommended on those two.
Me and my partner got our achievements after Russia, that's really late considering we messed up a lot. (I forgot to turn off damage and rules :P, we had to retire several races). If everything goes smoothly, the achievement will pop after Singapore or Monza.
Another thing I would like to mention - keep your distance with the other cars, one wrong tap and you could spin out, costing you some valuable points and time.
Happy hunting!