This is probably the best advise there's no real cut off then - otherwise the references back to Rose and certain other bits won't make (as much) sense...this is the best advise in the thread and I 2nd itLdude893 said:Start with "Rose" of the first series from 2005, it's the first modern Doctor Who episode. Keep watching from there.
You've got time, the latest season doesn't come until late this year.