48 hours is the maximum time that is given for the settings to change and for a custom domain to become available. Generally, it's a lot quicker than that. For Yola-bought domains, it's often less than 10 minutes.
Please note that this applies to type the address into the address bar - not if you are searching for the address using a search engine.
If you are unable to view your site, please click on the email link below for further assistance.