Last. The medical examiner said that the gun shot alone would have either killed him instantly or rendered him totally incapacited. The shell casing also fell into a pool of blood already present on the floor. Also said something to the effect that there was little blood from the gun shot as he had already bled out so much that it didn't fill his sinuses or come out his nose or mouth which it would have had it been the first wound.
Personally, I don't think she wanted to use the gun and only brought it as a back up because firing it would have made a loud noise that someone might have heard and thus having the possibility of her being caught red handed by police or a neighbor. She probably also would have been afraid that the gun would get wet from the shower and possibly cause it to not fire.
Let's not forget this was a head shot at close range. I find it impossible that such a shot could be received by a person and they'd still be able to get out of the shower and down the hall on their own. People shoot themselves in the head when committing suicide with a gun for a reason - instant death.
There's no question that he died slowly and painfully. A gun shot to the head at close range as the first strike would have taken him right out and rended him either dead or entirely helpless and nearly dead. The bullet went through his forehead, bounced around shredding up his brain and lodged into his left cheek bone. There's no way that he would still have had brain function enough to do anything - move, breathe, think, etc. That gun shot all by itself would probably have instantly killed him. There's just no way that it could have come first.
The ME is going to get on the stand and shread the story of the gunshot coming first. But what else can the defense say? They can't say that Jodi was able to get away from Travis, run to the kitchen for a knife and run back and stab him in order to protect herself because then it's definitely not self-defense - she could have kept running straight out of the house screaming her head off. Running BACK to the bathroom to stab him is premeditated murder all by itself.