Good Morning Bernard, 

Thank you for contacting the U of M Extension Service. 

Although we did get a little rain a few days ago, and they are predicting rain over the weekend, I would suggest you water the trees. 

Please click on the following excellent article about watering newly planted trees, and the time it takes for them to establish roots: https://extension.umn.edu/planting-and-growing-guides/watering-newly-planted-trees-and-shrubs

I would recommend a few inches of wood chip mulch under the drip line of the trees, a few inches away from the trunk. The mulch will protect the roots, keep the soil temperature consistent and retain the moisture. 

Good Luck!