You can find an overview of all the key dates for Edexcel AEA, GCE, GCSE, ELC and DiDA qualifications in chapter 2 of the information manual and in the UK and international key dates calendars, available at the bottom of this page.

Another useful tool is the online key dates calendar for general qualifications that has been devised by the National Assessment Agency (NAA) in collaboration with the unitary awarding bodies. 

This calendar, at www.modernisationonline.com/compkeydates/, gives an overview of administrative deadlines and other key dates (including an examinations timetable) for the UK awarding bodies AQA, Edexcel, OCR, WJEC and CCEA and common dates issued through JCQ.