my first year out they were rutting full on opening weekend. since it was my first year i didnt quite identify it that way at the time as i didnt really know that much about the animals. i had brought in a bull that came to my crappy calling, and then i found out about 30 minutes later he was a satellite bull amongst some others and a GIANT bull came through with his harem. opening day, my first year bow hunting and my first year big game hunting. that was a crazy sight to see!
Assuming your talking about opening weekend of archery that makes sense but with all due respect let's not confuse the height of the harem season or the build up to the rut, with peak rut. It is my experience that peak rut happens within a week or so of the Autumn equinox. This in my experience is when I have observed the most cows coming into to estrus. I see some cows come in with their first cycle much earlier, and I see some come in with their last cycle much later, but the majority come in within five to ten days of September 22nd or 23rd. In my experience weather only plays a roll in the activity of the rut and not the peak rut itself - but rut activity is a whole other topic. . .
I would say your best bet for calling an early season Bull is to use an Estrus call. . . One I have never come to master as I tend to over do it which makes most bulls cautious so early in the season. Most don't want to leave a harem they are working hard to build to go to deal with a bitchy cow in heat while their T-Levels are still relatively low. Most young rag horns or young bulls may show much greater interest so it will be your decision what you want and what you are willing to work for.
Wakan Takan kici hehaka
Respectfully,
Akicita