I live in SE Michigan so we have the same climate.
I am lazy, so I start after danger of frost has past (Mother's Day for us).
Materials needed: a paper plate, 2 squares paper towel, bean seeds, gallon ziplock bag, water.
1. I carefully dampen well (but NOT dripping wet!) one square of paper towel and place it on the paper plate.
2. Second, I lay out bean seeds on the wet paper towel/paper plate ensuring none of the beans are touching).
3. When all the beans are laid out on the paper towel on the paper plate, I wet the other paper towel and place it over top of the beans.
4. I place the paper towel/green bean "sandwich" and place it in the ziplock bag (do not close the ziplock bag!
The beans will germinate within 4 days or so (the root will starting coming out of the seed first; so this is when I plant).
By this time, I'll have my green bean row prepared with fence posts/crop netting so when the beans start sprouting, I place carefully place the bean root down, water in, cover with soil, and water a little more.
Done!