as I understand (others will chime is if I am incorrect), you can join before all the details of your business are decided and then make changes as needed. You may have to put *something* down for now, but that doesn't mean it's set in stone.
Do as extensive a search as you can for the names you like to see if any other centers have them already, or something too close to it. Since your website will probably be an important part of the business, see if the domain names are taken as well. A word of caution though: some domain providers alert their software to register names that get searched a lot in the hopes of squatting. If you see something you like and it's available, don't wait too long to register it.
"if it ain't fun, why do it?"