How long does it take to remotely schedule a show?

It depends on the Media Center PC, Mac or PVR's software.

Most devices that support IceTV Interactive get their update timing from the IceTV server, which is about 30 minutes unless the IceTV server is under heavy load. So if you schedule something to record it'll normally happen within the next 30 minutes, maybe sooner.

EyeTV is an exception to this rule: it only updates once an hour at the quickest setting.

Another thing worth noting is that if you schedule something that's over 5 days away, it won't be sent to your device straight away... it'll be sent when it's in the next 5 days. This is done intentionally as some of the software we work with doesn't like scheduling programs if there's no EPG data downloaded for that program yet (ie. the remote record request arrives before the EPG data does).