You don't have to wait 5 days for the transfer. If it's registered elsewhere, just change the nameservers at your current registrar. Heck, you don't have to even to a registrar transfer if you like your current registrar. Most of mine are registered at GoDaddy.
In the meantime, you can go to your DreamHost Control Panel to manage domains and set up some Fully Hosted (sub)domains. Also in the panel under Manage Users, or even the upper right corner's Account Status to find your machine name and ftp to machinename.dreamhost.com then upload your site's files into your home directory's yourdomain.com account.
To use your new site before the transfer, see this wiki article: