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Typically http://web.mit.edu.ezproxyberklee.flo.org/nse/education/grad/phd.html is supposed to have the most up-to-date information, though currently (July 2015) the website reflects May 2013 version which is not the up-to-date version, so you should refer to the Oct 2014 document linked above.
Typical Timeline For Taking courses
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