Let us know how it works for you.

I plan to use it early fall, probably apply twice: September 1 and September 15.

Aerate, fertilize and overseed October 1. I'll give you updates around that time.

Why are you going to aerate?

Do you know what kind of fescue you have? and where you are going to get the matching seed?

Never mind the question about what you have. I just found it on another post of yours. But why aerate?

I think my lawn/soil is getting compacted.

All the sources I read say aeration is good for the lawn to improve the microbes, drainage, lawn health, etc.

Is there a problem with aeration I need to know about?

Here in sw MO Tenacity seems to spare the tall fescue lawn and kill the very tough to kill wild violets, nimblewill, and the unwanted unidentified grasses that poke up higher between mowings. It also seems to kill liriope (glyphosphate will kill it only immediately after cutting/mowing the tops), also euonymus is killed. It is expensive but a very little goes a very long way. I spray with a small household spray bottle. Affected plants turn white due to lack of chlorophyll production. Be very careful about overspray onto wanted plants.