Fairly easy achievement if you find the right spot. You can get this as soon as you enter the Narco Road DLC. What you are going to need to do is line up your helicopter with where you are aiming for, jump out, and then it's just trial and error diving and pulling back.
Here is a video of the location I found the easiest to get the achievement. The cliffs give you a target to aim between :) I did this within my first few tries.
Pro tip - get a friend to line up the helicopter for you and aim the passenger side of the helicopter towards the target. Marking the target circle helps too.