Tell a user their chosen name is taken before clicking submit

Tell a user their chosen name is taken before clicking submit

I had to try out ten different usernames when signing up for Seocheckout and go through the process multiple times just trying to come up with a unique enough name. In the end, I chose a combination of my first and last real name. On some sites, such as Gmail, it will tell you on the page whether or not your username is already taken, even before you click the submit button to sign up. Is this a possibility for seocheckout?