In Wyoming, with a rifle, you should have good hunt success in the later season (I wouldn't wait until the end of that late season). The bucks in the early seasons, especially mid to late September, are rutting hard which makes for fun and exciting hunt. By mid October, the antelope will be herding up. You'll be able to judge multiple bucks together, but there will be many eyes on you. By late October, you may find herds of 100 or more. That's a tough stalk, but still doable with a rifle....If you wait in until late and end up with a snowstorm on your hands, you may be sorry. Hunt a week or two either way of October 1 and I suspect you'll be fine.