While your site isn't live at the domain, it's possible that search engines could crawl your subdomain development site. If you don't want your development site to show in a Google search you can try to set the site to no index no follow.
1) Sign in to the dashboard.
2) Under Settings, click Reading.
3) Find the Search Engine Visibility setting at the bottom and check it.
Keep in mind, its up to the search engines to honor this request.