Michelle
If I understand what you are asking, there is no fixed period the DWP can review your claim at any time once three months have elapsed since the Decision to move you to the WRAG was made.
If you contact the DWP office dealing with your claim then they should be able to tell you when you will be reassessed as the information should be recorded on the ESA computer system.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
