It usually takes anywhere from 2-48 hours for a domain to fully replicate changes, additions, or deletions across all nameservers. It all dpenends however on your ISP. Updates maybe within minutes for your neighbour, but may take up to a week for you or vice-versa.

The reason for this is the nameservers for your ISP update at different times during the day/week. It is varies from ISP to ISP and it is rarely possible for DNS take a week or more to update.