What is the common dates to apply and then start a PhD in western Europe? I am currently looking for a PhD in computer science for the fall in France, Germany and Switzerland. Although I still find some offers, I think applying in June is quite late. 

What are the common periods to apply for a PhD in those countries and in which month do people usually start their PhD? Is it common to start it at the beginning of the summer semester?
In most german institutions (and in Switzerland also I think) the PhD studies are completely independent of the semesters. New openings depend on when funding becomes available and you will mainly be an employee of the university, not a student.