Pre-Propagation Support allows your customers to view their websites before they have been registered with a company, or are even resolving to a domain registrar!
To do this login to helm and select your domain.
Click the Domain aliases icon
Then add something like: my-domain-name.fast2host.com or f2hxxx.fast2host.com and click save.
This will map mydomain.fast2host.com to your domain webspace hosted with us. You do not need to wait for DNS because fast2host.com DNS is up to date.