Come on you Minnesota hunters help this guy out!

Young Hunter,
From my experience in Iowa, I try not to call and rattle until the last week in October or the first week in November. Until then, I try to set up in travel corridors that the deer frequent.

Note: the following has worked for me and I am in no way a professional or expert.

As for the rattling, you want to try to mimic an actual sparring session between two bucks. I start out with a light "tickle" of the horns, which mimics the initial contact between two bucks. After about 20-30 seconds of light sparse rattling, i tend to get a little more aggressive and knock them around harder, and let the mass of the rattling antlers deaden the sounds. I normally do not exceed a rattle sequence of more than 3-5 minutes.

Also, I usually rattle late in the morning, 9:30am-10:30 if I stay in the tree that long, and only if I haven't seen any action for a while.

Hopefully some guys from your neck of the woods can help you out with more local techniques and timing.