From my experience it really depends on the area and hunting pressure it has seen and the weather. Larger bull are off by them selves by later Oct, the herd size of the cows are spread out and fewer in numbers, small bulls still may be found running around with the cows. By Oct. if the snow has moved into the area (12?-24? for more than two weeks) they are lower near winter range. Typically they have moved onto private ground and ranches in the valleys. I have had luck and seen more lower near meadows with access to the timber for the day time. I see a lot of singles and small heard?s move from the timber above at day break down to private ground and back up to the timber at night. Big bulls will stay in the dark timber as long as possible even with 12" of snow as long as there is a good feeding self and water near by.
What area are you looking at?