GP is applied each time a user logs on to the network right at the time of logon so there really should be no need to force policy to a user. However there are circumstances when you may want to control the frequency that policies are refreshed throughout the day or prevent GP failures when accessing the network over a slow link or connection. To do this open GP and navigate to Computer Configuration => Administrative Templates => System => Logon and enable the ‘Always wait for network at startup and logon’ policy. Enabling this policy forces a computer to contact a DC (which then will apply GP)at logon and prevents the use of cached credentials over a slower network. The other policy setting is called ‘Group Policy Refresh Interval for Computers’ and is located just down the tree in the Group Policy folder. This setting allows you to set in minutes how often computers on your network should query for GP updates. This is usefull in a busy environment where policy changes occur frequently. Setting a shorter time allows computers to check more often throughout the day for updates where in a smaller environment where changes are less likely to occur, a longer length of time would be suitable.
Hope this helps!