well my exam timetable/ statement thing from school tells me that my AQA History and OCR Chemistry coursework are both due in by May 15th - soo i would assume it would be the same date for Edexcel as well
Yeh you have to give the teachers time to mark t hem and moderate them. I do English Lang on EdExcel and we've just given our coursework in 2 weeks ago, and the English Lit crew gave theirs in last friday. They split it up at college to allow them to moderate; I would say before the 15th May, if this is what you have on your exam slips to allow for moderation.