Aerate as soon as possible. If it happens in the next couple of weeks, overseed and fertilize right after. Aerate and seed again in Fall. If your yard isn't huge, it shouldn't be too expensive. If you wanna save some money, just pay to have someone Aerate and get seed and fertilizer yourself. Turf Supply shops can help, if they allow the general public in there. (They do in my state). Folks there will know what to sell you.

Make sure you don't put any herbicide or pre emergent if you seed. You don't have to fertilize all year. You can get by doing it late fall and first thing in spring, to save money. Aerate and seed every year for a few years. Don't cut it too short. Bad for grass.