i assume you mean as soon as you make a change to any of the settings.
Policies are affective on the client as soon as they run a policy update. By default a client waits 90 minutes, then an additional amount of time, which is randomly chosen between 0 and 30 minutes....that means that within a maximum of 2 hours, and changes should be in affect.
I don't have a station with me, but there are settings in the group policy under the Policies category, that lets you define a new standard for refresh cycles.
Login scripts wont help you, as the login it's self, envokes a policy refresh.
I don't really see why you have a need to (on a working network), have this functionality, you shouldn't really be changing the settings so offten that a 2 hour delay is affecting it. Again, this is only AFTER you have changed settings,
If you DO wish to force a policy, if you are at a terminal, Start > Run > gpupdate /force > ok. if you have changed machine configs, you will be asked to reboot, however, unless you have changed settings that run real time, i.e hardware config, your settings should be applied next time they are referenced.
If you wish to force a remote refersh of the policy, our friend, Sensei Mar-Elia of GPOGuy.com has this little tool for you.
Remote GP Update
Hope you found this post helpful
Neil J Cotton
njc Information Systems
Systems Consultant