Hard to say when it will emerge but put it in a location where the newly emerged moth can climb a twig or stick to properly inflate the wings.

It appears to be the cocoon of the Polyphemous moth, but there are others that are similar. Is the cocoon open on the end or completely sealed up?

It's completely sealed, looks like a perfect capsule. I've been googling moths and wondering if it could be a luna moth? Some of the images look just like my cocoon. I even found this article where it mentions that they will wrap their cocoon in birch bark.
http://entnemdept.ufl.edu/creatures/misc/moths/luna_moth.htm

I've never seen such a moth around here, then again I wasn't really looking. I hope I'm around to see it emerge. I think moths are beautiful.

Luna moths do occur in Michigan, and can be seen in Lunesta commercials year-round. They do use a vertical surface to form the wings properly.

I sort of leaned it against the base of one of the shrubs. Should be able to grab on easily. It's nice and protected there. Thanks for the tip. I'm so curious about it. If I miss it I'll be so disappointed.

A cubic-foot box with some screen over the top and various vertical sticks inside and placed in a garage, not right in a window, will likely let you see your moth, but you have to remember to check every couple of days for what could be weeks. Then you can let it fly away.