Tire Rack recommends tire rotations every 3000 - 5000 miles (4828 - 8047 km’s). This is confirmed with other sources.
These tires were installed new on March 16, 2013 at 95,205 km, so in four months I’ve already put on 9,456 km. Time for a rotation for sure. I can actually see a difference in tread depth and edge wear. I’ll monitor mileage more closely in the future.