Should I fry the chicken first or should I pressure cook it first?
Frying the chicken tends to set the muscle fibers by drawing moisture out. An example of this would be taking a thin (1cm) cutlet and frying it until both sides start to turn golden. It will be pretty dry and hard. 

Pressure cooking it on the other hand tends to soften the muscle fibers without drawing moisture in (if anything, its putting moisture in). 

So, ideally, you should boil/pressure cook your chicken prior to frying in oil (though do make sure to drain the chicken first to prevent splatters!). Additionally, you should undercook the chicken slightly in the pressure cooker since you'll be finishing it in the fryer. 

If you are broasting the chicken, then you are going about the recipe incorrectly by frying then pressure cooking it. When broasting, you should pressure fry - if that makes sense.