There are several ways to be able to go to Championships. It would help you to read the Championship qualification criteria found
here..
Registration for Championships a while back (
FIRST calendar) with registration available for Tier one teams the last week or so.
FIRST saves spots for those teams that will qualify through their performance at regionals this year. Those teams will have the opportunity to sign up after their regional wins (as per the qualification criteria).
If your team does want to go to Champs, I recommend that you do get on the waiting list. Many of the teams who will qualify through their regionals may already be signed up so spot may become available later in the season.