Ohio lawns are cool-season grass — Kentucky bluegrass, tall fescue, perennial ryegrass. That single fact sets the whole calendar, and it is why advice written for Georgia will ruin your yard.
Spring
Hold off on fertilizer until late May. Feeding cool-season grass early pushes top growth at the expense of roots, right before the summer that will test them.
Late summer into fall
Mid-August to mid-September is the single most productive window of the year: overseed, aerate and feed. Grass planted then has two cool seasons to establish before its first summer.