Can they extend a traffic stop to wait for a K9?

This is the specific scenario the timing rule was written to address. An officer completes a traffic stop's business and then holds the driver until a K-9 arrives. Absent independent reasonable suspicion, that additional detention isn't justified by the traffic stop that's already over.

The State's usual response is that the stop wasn't complete, or that additional suspicion had developed. Both are examinable.

What defense counsel looks at: when the tag and license checks came back, when the citation was written, whether the officer was still working on it or had set it aside, what questions were being asked during the wait, and what specific facts the officer says created the additional suspicion.

Nervousness, travel from a source city, and air freshener in the car are the standard recitations, and they've been found insufficient on their own in a number of cases.