From what I've personally seen it's only been the younger bucks engaging in any kind of rutting activity. I've seen some 1.5/2.5 year olds doing some chasing, but the couple of older bucks I've seen have been leaving the does alone.

Now a buddy of mine saw a bunch of bucks chasing when he was out the other night, but it sounds like only one of them was even 2.5. Another buddy had 3 bucks chase a doe through his yard last night, but couldn't tell how big they were.

I think if a doe is hot, she is going to get some attention. Otherwise the heavy chasing hasn't begun as far as I can see.