How Can I Migrate My Domain to HSR With Minimal Downtime?

The first step is to configure your domain and everything that relates to it with us. This includes asking us to pick up DNS on it. You should map the domain in Apache/Zope/etc. as needed, create any email accounts you need, and otherwise replicate your current domain setup on our servers. A couple days before the move you should lower the TTL's (Time to Live) on your A records where the DNS is currently hosted to 600 seconds. About 24 hours later you can then safely change the nameservers for your domain at your registrar and wait until the change is fully completed. This will keep any downtime to an absolute minimum. About 24-48 hours later, get any email at your old MX and have them drop DNS and email service on your domain(s).