What is the correct way to manage my lawn?

I like in the Chicago area and have moved into a new home (8 years old). I am unaware of the previous owner’s lawn care techniques. The reason for my question is that today I saw my first Japanese Beetle. Some websites say to treat for grubs now with the first sighting of a Beetle. The lawn looks good overall, but I do not some thatch. The yellow spots in the lawn are minimal. I do have an inground sprinkler system. My question is when is the best time to dethatch my lawn, and apply appropriate chemicals throughout the year in Chicago? What products and dethatching techniques are recommended? I appreciate your thoughts in advance!