Section 306. Change of venue; procedure

The  bringing of an action or
  proceeding in the wrong county shall  not  be  deemed  a  jurisdictional
  defect,  but the court may of its own motion and must on the motion of a
  party defendant transfer the action or proceeding to  a  proper  county.
  The  motion by the defendant for such relief must be made in writing and
  on notice and must be filed with the  clerk  before  or  at  joinder  of
  issue.  It  must  specify  the county to which the defendant desires the
  action or proceeding to be transferred and must state under  oath  facts
  showing  that ground exists for such transfer.  In the absence of timely
  motion by the defendant, he shall be deemed to have waived any objection
  relating to proper venue, except in the case of a real property action.
    The transfer of a real property action from an improper to the  proper
  county may be had at any time by motion or otherwise.