When is best times to autumn in October?

We are planning a trip to do the Tateyama Kurobe Alpine Route in October .
These are the following dates we are considering for our visit:
Oct 6
Oct 13
Oct 20
Would early, middle or late October be best to see autumn colors?

This website publishes autumn colour reports at various locations - I would suggest checking those to see if the route has been featured and at what time of year (most places have been on there at some point, especially those famous for autumn colours).

Are there any specific places you want to see autumn leaves?

October is too early in most of the country, so you'll have to visit Hokkaido, northern Tohoku, or mountains in other parts of the country in order to see autumn leaves in October. The later dates are better.

This year, even as far north as Iwate, they issued an autumn report at Geibikei Gorge in which the leaves were listed as just starting to change on Oct 20:
https://www.japan-guide.com/blog/koyo20/201020_geibikei.html

In 2019, on Oct 17, they listed Hakkoda (Aomori) to be at its peak, although the report says it was a longer-lasting year than usual:
https://www.japan-guide.com/blog/koyo19/191017_hakkoda.html

Nikko seems to peak around Oct 20 each year.

Mount Azuma (Fukushima) was peaking on Oct 27 in 2017:
https://www.japan-guide.com/blog/koyo17/171017_bandai.html

If you click on any of the autumn reports and look at the right side, you'll see that they have all of their autumn reports from 2008 to 2020.

Thanks for the earlier replies.
We will be doing the Kurobe Alpine Route.

The foliage season is said to be from mid Sept to early Nov, but mid Oct is a safer bet. Koyo is most spectacular on the mt slopes around Kurobe Dam area.

https://www.alpen-route.com/en/about/seasonal.html
https://www.alpen-route.com/enjoy_navi/autumn/
https://www.japan-guide.com/blog/koyo19/191031_alpen.html