How did the drag curls treat you bro?
On your shoulder days bro instead of alot of pre workout stretching (which can actually be a bad thing) you might want to try 10-15 min of 120-130bpm cardio to fill your muscles with blood. Then arm circles in both directions with 5 lb plates. Then a rotator rehab type movement for like 3-4 sets of 15 with 10 lb plates(
Rotator Cuff Exercises for Weightlifters - YouTube)
the first movement he does and also at around 1:25(without the funky bar thing)
I do this on shoulder/back/chest day. Everything shoulder related will be full of blood and have a slight pump and be ready to pound iron. Then do your stretching post workout.