fathom - 2:55 am on Dec 27, 2002 (gmt 0)

There is no risk at all. It is best to set up your site on the new host -- wait 48 hours and then drop site off the old IP.

This ensure that all world-wide ISP's have access to the old IP while waiting for the DNS change, rather than visitors and bots receiving a 404 error because their particular IPS has not updated.