Without a good, reliable soil test to guide you the only thing you can do this fall is apply organic matter, shredded leaves and compost. If your soil pH needs to be adjusted this fall is the best time to do that because it takes time for either lime or sulfur or what ever to help make that change.
In addition to contacting Rutgers about having a good, reliable soil test done you could dig in with these simple soil tests,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
to see what more your soil might need.

You don't say where you live (a communication sin in my opinion), so I can't help with the question of, "is it to late to (fill in the blank)?" With fescues you need to overseed every fall. If you have enough sunlight to grow Kentucky bluegrass, you won't need to overseed ever.

You can apply compost but I would apply fertilizer instead. I would apply now, in a month, and in two months if you still have green grass. Corn meal and alfalfa pellets are my favorite organic fertilizers but others have excellent success with soy bean meal. Even used coffee grounds work very well. The rate is 10-20 (or double) pounds per 1,000 square feet. The compost app rate is 1 cubic yard per 1,000 square feet.