As for shipping cattle from the high country to lower ranges, mite have depended on the weather.
I have started as early as mid September and gone as late as the first of December, a couple of years have left them on the high range all year.
(from Moffat County)
We own the land so don't have to worry about grazing rules ( which mite have time limits on how long cattle could graze on the Goverment land )As for an average I'd say mid-late October.
As for Cattle heading to the sale market, could also be anytime, depending on the sale, filling a contract sale or trying to hit a good price on the open sale market.
For the spring time it seems that the weather again sets the time frame, with Mid-late May being the average.
"Angus" John