Hi, Jo. Folks from that part of the world may chime in with more specifics. I have visited a Viehscheid, and I am thinking it was around about the 23rd or a few days before. That said, there are so many possibilities: Südtirol, Tirol, Bavaria - Switzerland, I suppose is within your timeframe, too.
Some of the keywords I found useful are: Almabtrieb, Viehscheid, Alpabzug. There are others in Italian. I visited a parade outside of Innsbruck in Mutters. It was easy to get to on public transportation.
You have lots of time to research since most of the dates are not published till the end of summer. Try some sites like these to get an idea. You can use the translate function if needed.
https://www.tyrol.com/things-to-do/culture/tradition/cattle-drives
https://www.austria.info/de/aktivitaten/stadt-und-kultur/brauchtum-in-osterreich-leidenschaft-fur/almabtriebe-in-osterreich
When I visited Mutters/Innsbruck, I was on my way to Padua, so similar to the trip you may be making. Trains from Venice, then onto Verona and on north are easy to navigate.
Have fun planning. Oh, and I found YouTube to be helpful in checking out some of the locations and past parades.
Debbie