Sorry for this generic answer but it is the truth.
When the snow gets deep enough to cover their feed up high to where they can''t get to it. It might start in October or December, it just depends on the year. I know of a herd in Utah that winters at 9500' + just because the wind blows the snow off of the high ridge that they live on and there is feed all winter long.
Like this last winter for example. Where I live here the winter was so mild I never saw any elk come down as usual. In general there are several hundred not far from the house by December/January but they never made it all this year.
So you've booked an outfitted hunt this year. And you're going to get to ride horses into the mountains to save your legs and your back.
I've met lots of guys who've been in this same situation. They figure, "heck, how hard can it be?" But, I assure you, if you don't learn to get along with your mount for the week, it's going to be a bumpy, scary, noisy, and life threatening experience.
First, let's start with the horse itself. A horse trained under western style has 4 gears. The walk, trot,...