Establishing new lawn
Prior to preparing your soil, conduct a soil test to determine if you need to amend your soil. The University of MN Extension has instructions at this website regarding how to obtain your sample: http://soiltest.cfans.umn.edu/
Once you receive the results of your soil sample back, you will know if you need to amend your soil (adding compost, black dirt, peat moss, nitrogen, etc.) to make it more amenable for a lawn (grass) to grow. Then you need to decide if you want to sod or seed your new lawn.
Either way, you will want to make sure the amended soil is firm (patted down) slightly before you either place down the sod or over seed. The best time to seed in Minnesota is late summer (mid-August to mid-September) so you have plenty of time yet to get things done.
If seeding, you have more control over the type of grass you want to grow in your lawn as you would if you put down sod. Ideally, sod would be cut no more than 24 hours prior to delivery to your home and it should be laid as soon as possible, or within one day of delivery to avoid it drying out.
For tips on seeding and sodding home lawns, please refer to this webpage: https://extension.umn.edu/lawncare/seeding-and-sodding-home-lawns