Courtesy of Ryan Divish, from today's pregame media session with Eric Wedge:

Franklin Gutierrez has satisfactorily cleared workouts with the Mariners and will now head to Arizona for extended Spring Training. Once that's complete, the plan is for Guti to rehab with the Rainiers. Wedge stated that it was likely that Gutierrez would take the full, or most of, use of his rehab stint before rejoining the Mariners. For position players, rehab assignments can last up to 20 days. That should give you a rough timeline for when to expect Franklin back once he, if he, begins an official rehab assignment.