I don't see him getting shot first.
For one thing there is not much blood from that wound and he would have been incapacitated. Why so much blood in the bathroom and down the hall?
You can tell the blood from the head wound just went straight down his face.
Why 29 stab wound on head, back, neck, front, etc if already shot in the head?
Some of the wounds look like he was moving, others are packed together.
The gunshot path looks to me to be from someone standing over a prone body. It goes from the top of the head downward. No way he could have been standing in the shower and got shot there.
IMO, he was shot first. It makes much more sense. He was sitting on the floor of the shower stall. Jodi had a camera, probably in her right hand, and pulled a gun from her striped pants with her left or had it hidden behind her in her left hand. She probably clicked a flash picture to blind him for a second as she pointed the gun and aimed a downward trajectory into his head, from his right side with a .25, which is a slow velocity weapon in the first place. (My husband says "everyone knows you do not expect to kill anyone with a 25." I didn't know that.) The bullet did not even have enough speed to penetrate the left side of his face. It lodged in his left cheek. Makes sense from the position he was sitting in the last picture. Also makes sense in terms of the rest of the crime scene. She did not expect him to survive the gunshot and had to scramble to get him down as he tried to escape. Also, the medical examiner did not state that he knew for certain which wound came first. He left some leeway. It was his opinion that it was the knife wound. But, think of how awkward that would have been for her to drop the camera from her right hand, grab the knife to attempt an upward thrust to his heart. The angle would have been wrong if she had had the knife in her left hand. Additionally, she turned on the shower after stuffing Travis in it, which would have removed blood from his face and possibly gun powder traces.