Once you make changes to your domain with the registrar you purchased your domain from, the changes will take anywhere from 5 minutes to 72 hours for propagation to occur depending on your ISP and how often they update the DNS records.
Domain propagation is the process of your registrar handing off the changes of your domain to root DNS servers, ISPs acquire records from the root servers, ISPs to other ISPs and so on until you see the changes reflect on your computer with your internet service provider. Some service providers update their records more often than others and receive changes faster. As a result of this, often you will not be able to get to your website by its' domain name but a friend can. Simply wait out until the changes propagate to your ISP. In the meantime we provide you an IP and temporary address in your welcome email which allow you to start working on your site immediately!