yep the earliest I've seen hardhorn bulls is Aug 20th or so. Bou are just fickle and go where they want. I've talked to a lot of guys that fly in and have fewer animals to hunt than I do on the Dalton. If you're flying in, just realize that it is people you are trying to escape, not increased animal numbers. If the weather is warm, the bou will be high, on the ridges to escape the bugs, and if the weather is colder they will bunch up and travel. Many times we have hunted for a week or so without seeing anything, and the next day we will be in the middle of 5000 animals. Bear in mind that they are herd animals, and the herd can move 25 miles a day,,,,,,,so here today,,,,gone to Maui,,,,whether you fly in or not. At least on the road you can shift base camp to follow the herds location, with a fly in, you are restricted to where you can hike from the airstrip.
Another thing that a lot of guys from outside don't realize is that airstrips in Alaska are limited and nobody OWNS them. So even if you pay big bucks to get flown in, there is nothing to keep a private pilot from flying his buddies in right on top of you. And there are a LOT of pilots in Alaska. The other thing you need to know about flying in is the difference between an air taxi and an outfitter. An air taxi will be cheaper but they will fly lots of guys to the same location if they are requested to. They will usually not suggest where to go as this infringes on the outfitters business. And there are laws that govern the differences between the two and the services they are allowed to provide.
Not trying to be a buzzkill but it is stuff that guys from outside need to think about before putting big bucks on a fly in hunt. Good luck