In theory, if you do it correctly, from the outside world's point of view, there should be no downtime at all! Obviously, to start with you'll need to open your account with us. Once done, you'll be able to associate a domain name along with that account. Clearly this domain will not currently be with Umbrella Host, and so to let our systems know of its existence, you will need to purchase hosting to associate the domain name to the account.
That domain will now appear inside the top drop-down menu in the 'Manage Services' section under your client area.
Once setup, you'll have a login to the eXtend Control Panel for your hosting account which will be included in the welcome email.
Login to your controla panel, on the main page of that panel at the bottom, you'll see the username, password and IP address for your FTP account. You can use them to upload your website to the server. You'll also see a link marked 'Temp URL'. If you click that link you'll be able to test the site you have uploaded to us to ensure it is correct.
Also inside the eXtend Control Panel, you'll see the 'Email Configuration' button. For inside there, you'll be able to setup all the POP3 mailboxes, catch all forwarding email address and so forth that'll need.
Once all that is done, to activate the account, you'll have to place that domain name onto our nameservers. In the case of a .uk domain, you'll need to ensure that the IPSTAG for your domain is set to EXTEND by the previous host. Many domain registration companies supply their customers with a control panel so that customers can make those changes themselves. If the domain is already on the EXTEND IPSTAG, then customers can move the domain onto our nameservers by accessing the 'Manage Domain Parking' section of their control panel. Customers will then be warned that domain is not on our nameservers and have the option to change those to ours.