Before planting grass, you should turn your attention to eradicating the poison ivy.
The irritating oil of poison ivy is present in all plant parts and will persist in dead vegetation for over a year. Take precautions when handling any plant parts or clothing that has come into contact with the vines.
There is, unfortunately, nothing that will "choke out" poison ivy. Your options are to use a chemical product to kill it or to dig it or pull it out by hand. For small plants (seedlings), invert a plastic bread wrapper bag over each of your hands and use them like gloves to pull the small plants, then just turn them right side out again, with the plants inside and dispose of them. Always wear gloves or use the plastic bag idea when handling this vine.
If you have larger, well-established poison ivy plants, you will need to spray them with an herbicide. Choose one containing triclopyr or a product containing a 3-way herbicide that contains 2,4-D amine, dicamba, and mecoprop. These are the most effective on poison ivy. Extra caution should be used to avoid applying these products to adjacent broadleaf vegetation as the chemical will kill any broadleaf plant it touches. Two applications, three weeks apart should provide a substantial reduction in returning plants next spring. Spot treating next spring in late April, or early May may be necessary to remove persistent plants. As always, be sure to follow all label directions carefully when using a chemical application--both for your safety and for the safety of your other plants that are nearby.
Some websites recommend using an herbicide containing glysophate (one common brand is RoundUp), which will kill any plant it touches, broadleaf or narrow leaf such as grass. However, that chemical has been linked to cancer, so I do not recommend it.
The information in the links below will give you information on identifying poison ivy and how to control it.
The best time to seed a lawn in Michigan is late summer or early fall, but it can be done in the spring also. Your first step to prepare your area for grass seeding is to do a soil test, ;which will tell you the soil's pH level, the consistency of the soil, and list any nutrients that need to be added. A self-mailer soil test kit from Michigan State University's horticulture research lab is available at the link below. Full instructions are are there and also come with the kits.
Below is information on establishing a lawn. It also includes a discussion of various grass types and will help you select the best one for your area.