As a guy going through UPT right now I can tell you do not worry about studying anything prior to UPT aside from knowing your Boldface/Ops Limits the day you show up. I'm not a guard guy so I'm not familiar with how things work, but I'm pretty sure by you telling them that you are already studying up for UPT without even having a slot you are probably not helping yourself.
We have dudes in my class that showed up to UPT having read every book and publication you can think of and they still continue to study 24/7 including Friday nights and on the weekends. In my opinion this is the worst thing those dudes can do. They do not hang out with us when we are hitting up the bars on Friday nights and now they are starting to seclude themselves from everyone else which is the worst thing you can do because that will kill your Commanders Ranking and ultimately make it harder for you to get through UPT. By the way those dudes that I'm talking about actually haven't even done that well in academics.
Now I know I got slightly off topic, but I showed up to UPT having only studied Boldface/Ops Limits and after 5 academic tests I currently have the highest test average in the class(which means nothing if you can't fly and aren't a good guy by the way).
Like everyone said before just focus on being yourself in the interviews and making the unit realize you're a pretty cool guy and would be a great asset to the unit.
Personally for me if I were on a combat sortie I would much rather have a dude on my wing that went out to the bar with me last night, got wasted, backed me up in a fight, and then split a cab ride home with me over someone who knows the DASH-1 by heart and studies 24-7. That's my .02.