[nznog] .co.uk zone changes.

Hi, How long does it take for changes to the .co.nz domains take to be reflected in whois and dns ? I am not native to the region, so don't have existing experience with this. A client of mine registered a .nz domain for a project of theirs through melbourneit. I changed the dns servers on their site, and it said that the change has been submitted, but 'dig ns theirdomain @202.46.190.130' still shows the original nameservers, as does whois. Any clues ? cheers -a