Entry to CRGS is via the Essex 11+. The Consortium of Selective Schools in Essex (CSSE) administers the exam on behalf of the selective schools in Essex and it's my understanding that the head teachers from the consortium schools take it in turn to set the papers.
For 2009, the CSSE website states:-
11+ Test Date for September 2009 Entry will be held on:
SATURDAY 22ND NOVEMBER 2008
Registration will commence from the 1st September 2008. A full Guide to the forthcoming 11+ and registration form will be available on this website from the end of the Summer Term 2008. The CSSE cut off date for registration is 3/11/08. We are unable to accept registration prior to the 1st September 2008. Please be advised this office is closed during all school holidays."
So you've got loads of time before you need to do anything!