Blu-meanie,
If you stay at the balloon field RV park, which can handle more than 6000 RV's, you could get by without reservations at all. My son and his family, who live here in Albuquerque, have taken their 5th wheel to the park on the day they want to stay and get the RV and slideout set up, then come and go in their car to their RV. That way they are there at the balloon park on the morning of launch time and not have to drive at 5 in the morning and not have to put up with traffic and a place to park. They take the shuttle to the launch field and buy breakfast burritos and hot chocolate They do it about every other year and have never had reservations. If you want to stay in the limited area with full hook-ups you will need reservation one year ahead of time. If you want to stay at a private RV park or a hotel you will need reservations ahead of time.
We have never stayed at the balloon RV park because we live so close to the Balloon park as jalag and his family know. Yes, we get together with Jim and his wife when they're here.
george