I'm looking at getting a 3 year old, 14.2 h Quarter horse. I want to really take my time with her. I don't mind if I can't ride her until she's 5 (i'm very patient, and I want a solid healthy horse). My only question/concern is that her owners now have already put a saddle on her. Is that okay for her back? What are some thoughts about what age I should continue with putting a saddle on her? Or if she's okay to go ahead and continue?