I was a lot like you. I wanted to do everything I could when I wasn't in a formal training environment and to use my time wisely to prep. You could buy an IFR course for a few dollars online and watch DVDs. It may provide some graphics and things to think about when you hit the academics for instruments and navigation later on. You could also then get microsoft flight simulator and practice with that. Also, listening online to liveatc might be good to listen to for some flavor of instrument comms.
However, all of that will not necessarily help you an iota when it comes to actually performing in the sim, flying the aircraft, or answering Air Force exams. It may alleviate an hour or so of study time since you kind of know a little bit about approach plates, enroute charts, etc..
Solid advice above. I gave you a few things you could do. I agree though, spend the time with your family or go do something you enjoy instead. You will learn the things you need to learn within the course.