The more thought I give it, the more I think he wasn't expecting her. JA's testimony is that she parked the rental car in the space she usually used, the middle spot in TA's driveway. The roommates would have had to noticed this car when leaving for work, if this is true.
JA also said that TA was up on his computer, with the Napoleon by his side when she was at the door. Even creepier, she stated she watched TA in his office before he noticed. TA's street looks fairly quiet, so again if this were true one would think that the dog would start barking at the sound of a car, lights on, etc pulling into the driveway. JA specifically said the dog didn't bark. I call BS. Unknown car, late at night = the dog is going to bark.
After murdering TA, JA sent an email that w/ something like: sorry I didn't visit, you were just too busy hon! don't be sad! what was the purpose of mentioning NOT visiting and the fact he was too busy? Knowing she wrote it thinking it would be used to prove her innocence, I think that this was his response when she pushed for a visit -- I'm too busy, working and getting ready for Cancun.
TA brushed her off, maybe rattled off his schedule for the next few days to prove how much he had to do. I think this is partly why she showed up at 4AM, because he'd definitely be there, alone (in his bedroom at least). I think she was also focused on doing something crazy with her hard drive, lap top and TA's lap top. Probably parked down the street, snuck in, did the computer stuff - taking about 1 hr and 1/2. Leaves, gets breakfast maybe and comes back after the roommates are gone and parks in the spot and pretends she's just stopping through, and maybe TA was already awake and cleaning, putting together the mop and surprise.
If the roommates didn't notice a random car there in the morning or hear anyone come into the house late that night (dog bark, door open, headlights, voices, the youtube videos) then I don't think anyone knew she was in the house at 4AM. And if TA was paranoid about his roommates suspecting he was having sex with JA, I doubt he'd want to watch videos in his office when they could want a drink from the kitchen. Also doubt he'd let her park in plain sight, either.
