Ok i live in iowa when should and do most people start hitting the horns i was thinking maby mid october ??/

it really depends on where you live i guess. Different deer populations respond to different things at different times. Pre-rut starts as soon as the bucks loose their velvet. During pre-rut the bucks start breaking their bachelor groups up, meaning they're running on their own. So who knows, maybe the big buck could hear the rattling and think he wants to show up to claim his territory again. But, it could also scare off other bucks that just got pushed out of their bachelor groups and are still a little uncomfortable. I personally wouldn't start until the rut, and the rut hits at different times in different locations.

I hunt N/E iowa and have had a lot of success using horns from the 20th on. And when you get towards the end of Oct. it's not a matter of if it's a matter of how long, before a buck shows up