So many smoke screens to work through in this case.
The more I think about it, the more I come to believe that JA waited until Travis's roommates were gone. If she came with the intent to kill, which I believe that she did, she would not want anyone to possibly know that she was there in Mesa. So for as long as there were roommates in the house, she couldn't let Travis know given the risk of him telling someone. While JA says that she and Travis went to sleep around 4:30 to 5 in the morning, he told his roommate that morning that he barely got 45 minutes sleep that night.
When Chris Hughes texted him around noon to confirm the conference call for that night, Travis did not indicate anything about JA being there. On the radio interview this past Sunday, Chris said that JA had emailed Travis after that big text exchange on 5/26 that she was going to talk to a lawyer and also tried to clear herself of aggressive actions, such as slashing his tires. Travis had shown that angry text to Josh Billings on 5/27 and Josh asked Travis if he was afraid of what JA might do after reading it. My point is that Travis was letting people know what was going on between him and JA; if he was free to communicate, it would make sense to let Chris know that JA was there and "how do I get rid of her..." or something like that.
My mind has been leaning towards JA not making her presence known until Travis's roommates had left and once there, she took over the situation with force, namely the gun. Neither Travis nor JA look engaged in the pictures of their "sexual interlude" that day and Travis is flaccid in the one picture of his genitals. He'd called her a dildo with a heartbeat and this may have been an act of revenge to further humiliate him, a way of flaunting that remark.
There are only two people who knew the truth of what transpired that day. One of them is now dead and the other is a pathological liar. We will never know with certainty what events transpired that day; we can only be certain of the outcome, and that was Travis Alexander was brutally slaughtered.