When your website is properly moved you probably want to see the changes at the new location. You can do that before the DNS is converted with the website: webpagetest.org.
You can do the same changes with this site as with your hosts file; testing the live site at a different IP.
Before you start a test you first have to fill in something. Under the tab [Script] of the settings enter the following code (change xxx.xxx.xxx.xxx to the IP of our server):
The test will now be done on the IP of our server regardless of where the DNS actually to refers.