Is "the clock" met when a suit is files or when the defendent is served?

Both.  You have to file suit before the deadline.  If you serve the defendant after the deadline, then you have to prove that you used "due diligence" in locating and serving the defendant with the court papers.  If there are long and unexplained periods of inactivity in getting the defendant served, then you could be subject to a "statute of limitations" defense.  So, be sure to documents all your efforts in getting the defendant served.