Don't have time for a full reply right now, but most of what is circulating as far as survival time of SARS-COV-2 is based on one of two surface-survival lab studies. What both studies reveal is that not only surface type but temperature and humidity (or moisture level) greatly affect the virus's viability time on surfaces. But that has been left out of people's interpretations of those studies, and out of circulation that later proliferates as a result of those studies.
There's the problem with that: the most commonly (it seems to me, personally, having looked at this obsessively) cited study mainly tested the survival times of the virus at 72 degrees F -- sort of "warm room temperature in Winter" -- and that temperature is very hostile to COV-2.
COV-1 is mentioned in coverage of the COV-2 study as having been found to live as long as 29 days on plastic and stainless steel at around 2 degrees C.
Personally, I was originally not touching horns for 9-14 days after receiving them -- at all -- while storing them in a quarantined storage rental that only I have access to (temps around 49F to 85F over the course of any given day, mostly in the 65-80 degree range during the day), and then washing the necks in dishsoap and water after unpacking. Upon finishing work, the horn was then washed again (neck only), allowed to dry out of the case, and then subjected to hot air both outside and inside, before being put back in the case and boxed into a cardboard box, which was then taped shut.
The logic there is that the virus seems to survive shortest on cloth and cardboard, out of the general surfaces tested and mentioned.
That way, the customer can leave it in the cardboard according to their own judgment, with the knowledge of when I last put air from myself in the horn before that post-work rigamarole began.
The main thing I wanted to point out in this post is that most of the info comes from one of two studies, the range of temperature in those studies is very limited and harsh for the virus (your house or shop could be cooler than 72F, and thus friendlier to the virus), and that citing citations of those studies should rightly note the limited scope of those studies (for your judgment's edification and your body's good health).
I don't think any customers have waited more than 3 days since I returned their horns or handed over their purchases. But they also know I have tested negative for antibodies twice and for infectivity 3 times, and that, as you can see, there are not a lot of people more strict than me in protocols right now.