It usually takes 24-48 hours for a domain to fully propagate. Propagation refers to the period of time taken for the changes made to the DNS take effect and being captured by ISPs (Internet Service Providers). This however all depends on your ISP, as it may update within minutes.
The reason for this is the local routers your ISP runs off of update at different times. If you are on Comcast or road runner cable, it is very common for DNS to take a week or more to update.
