Don't do it. The forms change periodically and there's some variation from state to state. Wait until you have your acceptance in hand and have a pretty good idea of what state you'll be going to and work through that state's AMEDD recruiting.
The whole package only takes about 4-12 hours, depending on how old you are (the older you are, the more jobs, colleges, households). If you really wanted to be an eager beaver, google for form SF-86. It's the security clearance form you need to fill out. It's not exactly what the Guard uses, but you could get a head start on identifying all past places you lived, went to school, etc. I wouldn't recommend it, but if you absolutely had to have something to do, that would be a head start.