I personally cant stand mice and would pay the money to hire someone to catch them instead of doing them myself, but i've heard of unsure if its true but of people poisioning mice, then them dieing like inbetween the walls and the odor is awful?

These can get very costly and if the carpet is over 5 years old or excessively worn or stained then replacement is a better option.Ozone can be use to mitigate many of the odor issues quite successfully  foggers can also work. both of these have side effects and can be dangerous if precautions are not taken. 

That she didn't want to make waves in her new place, but that it was actually the the other tenant "Smokey" causing the odor and that she was worried about her kids breathing it in.  

If the odor is not properly mitigated that will cause ongoing problems.

Another option is tear out any damaged material and ALL carpet and then see if you can get a place like ServPro to come in and mitigate the odor, they have ways and devices that pretty much fumigate the building and introduce a deodorizer to the building, not sure they can/will do anything for cat odor but it would never hurt to ask, they are a nationwide company and specialize in smoke/fire damage remediation. 

The team investigated tap water quality in a new PEX plumbing system, and examined the odor quality and chemical impacts of six PEX pipe brands (more than 70 have been certified by the IAW NSFI/ANSI Standard 61 as safe for drinking water).

For example, there is a famous lawyer named Theodore Olson.

I have known and smelt the odor in his apartment before and have confronted him about his smoking in the property but to no avail.

My question is would you list now so as to line up a good candidate pool, or would you wait until it is show ready without the odor, ideally mid-June?

One of my biggest problems was the odor and damage that was left from the tenants dogs.