Bachelor groups normally break up within a week of them shedding velvet.That would be roughly the first week of September.Not to say you couldn't see a couple together but things change after they shed velvet.
I wouldn't do too much sitting unless my glassing showed a regular pattern like coming into a field or waterhole.Often,they have no regular pattern.
Where I hunt,elevations run from 5,000' on the prairie to 9,500'at the top of the mountain.Most bucks will stay very high till mid to late Oct.All areas may not be that way though.
I would spend a lot of time glassing from vantage points but don't skyline yourself.When the deer is spotted and you let it settle in to bed,the hunting starts.Remember that once you start a stalk on a bedded mule deer,he may get up,stretch and move a few yards and bed again and often you can't see that happen.
Keep in mind when animals move back up the mountain in the mornings,the mountain thermals are drifting down right in their face.It is impossible to ambush them like that.That's why I say,glass,glass,glass and when you get one bedded,figure the wind and come in sidehill,from above or whatever works.
I see a specific buck leave a field headed up the mountain on a certain trail.That evening,he comes back to the field by another trail a quarter mile away.That is the norm.Keep an open mind but for the most part,forget sitting whitetail tactics.They can eat up a lot of time with no results.Mule deer will be where you find them and that's what the glasses are for.