Sign up with a hosting company that lets you upload all your files and set up all your databases even before your domain nameservers have changed over. That way, you'll have a copy on the old host plus a copy on the new host. Then when you change your nameservers, you are minimizing downtime. But - there is always a small chance you will have issues for a day or so while the change takes effect. Some internet providers take a day or two to copy over the new nameservers so they may still be looking at the old website while other providers are looking at the new one. So if you have dynamic content - say for example people place orders on your website, and your website saves a copy of orders - you could have a day or two with orders on both websites, and need to copy that info from your old site to the new one.
But, it can be done and sometimes it's necessary. I recently switched myself and I was lucky enough not to have any downtime. If you happen to switch to a web host that is physically close to your existing one this often minimizes the amount of time it takes to finalize the switch.
Elaine, a.k.a. RedScooter
- web graphic designer
- web code in simple step-by-step instructions
- web design & development, specializing in WordPress customization