You'll be ok. Your student ID number is your SS#. (I wish they wouldn't do that with SS#'S--but they do).
Go to the site that I have posted below. It will prompt you to register for an orientation session. You start the process off by getting into the computer system, taking a brief quiz, getting your e-mail address, etc. Once you are in the system, you will have the opportunity to see what needs to be done (left side of screen). It will list registration/orientation sessions, housing, food options, medical stuff and such. That will be your beginning.
Don't wait for your MyUVA book. Register today. If for some reason their site does not recognize you yet, it's probably just because someone hasn't entered you into it yet. At first, housing said to me something like, "we don't know you", I checked it everyday, and then I was there!
The biggest deadline you face is the housing one that is due on 6/8/07. This can be done on-line--so, hopefully, no big deal. Though I think that registration for orientation was supposed to happen before 6/1/07? My advice, is to go ahead and try to register now anyway-online.
http://www.virginia.edu/virginia/admitted/
I guess you could also be looking into getting the appropriate vaccines and such.
That's my best advice right now. Best of luck!