I've had much better success in transplanting oak trees, dog wood trees, and maple trees, when lifting them as young seedlings. I lift the young plants and place them in a 1 gallon nursery pot. After that they are usually up potted to a 3 gallon nursery pot and after they get a few feet tall, they are moved to their permanent location in the ground. My nursery plants are kept in a morning sun only location so that heat and water stress are not a problem.
For yours, you may want to lift it now as the spring is the 2nd best time IMO to relocate a small tree. But if mine, I would wait until fall, lift and repot after the tree is dormant. You are so far north, I don't know whether the trees do well over winter in pots or not. If you have no experience with growing the trees in pot culture, you may want to ask someone at a local nursery.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.