You have to be careful though - sometimes it *appears* to have taken place in minutes, but trying again in a few hours returns the old page. Things won't settle completely for 48 hours.

If you put the old site in maintenance and bring the new site up, people will be able to order as long as they can correctly resolve your domain name. There are other tips here:

http://www.zen-cart.com/content.php?...fferent-server