check availability first before Save to create a Group (OG)

I am using subdomain to let my users have a subdomain for their Organic Group.

Is there anything in here that I can let my users to check whether the subdomain is still available or already taken before they create their OG? What I know is that, subdomain will automatically be created when a user create a Group. But when they're creating a Group that has been already registered, they'll only receive an error message after clicking the Save button:
"There is already a @type_name with that @type_title. Please enter a different @type_name"
(btw it seems there's problem with the @type_name & @type_title not showing properly)

How about having this function when creating a Group?

Group Name: [enter-desired-Group_Title]
URL: http://[enter-desired-Group_subdomain_name].example.com x (Check Availiability)