Massage Gun Warm Up, Timing for Mobility workouts & What's the Best Physical Therapists for BJJ?

Question Time: Is before class the best time to use a massage gun? What is the best time of day to do your mobility vs when is best to stretch? Which is the best therapist for a BJJ Body- Chiro, Physio, Osteo or Massage therapist? Last but not least are the detailed points on how to get into the Hanging cobra position if you struggle with mobility through upper and lower back.