I don’t want to transfer an existing domain until I see how easy it is to set up a web site at WordPress. My understanding it was free to set up something, and then you pay when you are ready to transfer the domain name and publish.
You don’t have to transfer your domain right away.
All sites on WordPress.com get a free WordPress.com or .blog subdomain when the site is created, that functions just like any regular subdomain, and your site is fully online and accessible at that subdomain (provided you set it to public). You already have one of those.
You can experiment and build your site at that free address, even upgrade the site while still using the free address, and only switch the domain over to us once you’re ready.