Earliest here in northen europe is bird cherry, prunus padus, they get color already in late august or early september. I guess that's because they don't need a longer growing season. English oak, quercus robur, is the last to color, maybe one week into october. Introduced species tend to be very early or very late. For example chestnut, castanea sativa is very late while the amur cork tree, phellodendron amurense get lime colored already in late august.

Black walnut dump their leaves pretty early in my yard. I guess they turn a little yellow. They start pretty late as well.

The king of starting late is my zone 7 crape myrtle. By May it is thinkin about waking up.

Honeylocust and Kentucky Coffeetree color and drop the earliest. Don't care about the HL as much but its a shame as these plants leaf out late in the spring too.

In general Oaks color up the latest around here.

I think its a benefit for trees that color early as long as they don''t drop early. Many maples fit this bill.

earliest: sugar maples (if they are stressed - i know you said no stress) will color as early as july. Healthy trees that turn early - maybe ash, walnut
latest: without a doubt, weeping willows! Those suckers are green sometimes into December - and this is MN! Runner up award to silver maple.

You're right on those weeping willows!

some Sumacs start to turn in August here in Eastern PA. they really stand out when there's one red/orange sumac on the side of the road.

The first flush of leaves on my sycamores are already turning yellow. The outer leaves that grew later are still green and the branch tips are still growing. They do this every year. The leaves change and drop in about 3 waves with the last turning orange nov-dec.

After the first couple of chilly nights -doesn't matter when -the crapes light up in neon red and orange.

Earliest tree to "color". Robinia pseudoacacia. In late July (now) they turn that beautiful orange-brown from the beetles eating the leaves. Anywhere in the Mid-Atlantic they can be spotted against the green of the forest by their color. In another couple of weeks, they will be naked.