First remove the trigger from the gun before you start adjusting it. Once out you can set and fire it as many times as you want quickly and safely.
You will see the first stage engagement through a little window in the steel cage, with the first stage taken up it can be adjusted with a torx driver. Then you can adjust the spring tension of the second stage with the rear screw. If you want less first stage travel you will need to bend the little tab ahead of the blade.
Once you've got it how you want it, refit and enjoy!
God rest ye jelly mental men