A student who has got himself registered for Common Proficiency Test 60 days prior to the first day of the month in which CPT examination is to be held i.e. on or before 1st April and 1st October, can appear in the CPT examination to be held in June and December respectively. Common Proficiency Test examinations are held in June & December every year.
So, if you want to appear for CPT December 2014, you will have to register on or before 1st October, 2014.