Hopefully 2-3 hours as mentioned in the email I got.  Might be longer if DNS doesn't propagate though (still haven't set that up >_>).
Might be faster if you're using something like OpenDNS (unsure how their caching systems work, so IDK if it's any better).

Or you could add the line to your hosts file:

(don't add it now, as it will stop you from accessing it since the above IP isn't valid yet)