Once you buy a new domain and change the Namer Servers to the one of your host, it could take up to 48 hours for the DNS migration.
Waiting is not our style. Here is one way how you could start working directly.
When you type in a site into your browser (as Yahoo.com) first the browser approaches the DNS server. The DNS server provides the ip address of the host where the site is hosted.
The reason why you cannot see your site before the DNS is updated is because the browser doesn’t have the ip address of your host. Most likely, your site would be on shared hosting. So typing in the ip address directly into your browser won’t work either. (Here is an interesting wallpaper on How Internet Works)
To get around this, you could use the Hosts File on your computer to manually specify the ip address. For most of you, the host file would be in:
i.e. for Windows NT onwards, including Windows XP, Vista and Windows 7. If its not there, or if you are on a MAC, refer to this page to find your hosts file.
Open the file named hosts in a notepad. You have to manually specify the ip address of your site. Add it as the last line to the file, in the following format:
188.8.131.52 millionclues.com www.millionclues.com
Save the file. The browser first checks the host file for the ip address, and since you have given it there, you will be taken to your website.
Obviously, your site will be available only one the computer where the hosts file is specified. Others will have to wait till the DNS change takes place. But you can start working on the back-end right away.