Based on my trip there in 2012 and the information present on
this website, I would say mid to end of November.
It is probably safer to get there around mid-November since you can head for the higher grounds (near Kyoto, that would be Takaosan and Hieizan) and get some autumn colours early in the season if things get unusually late.
Back then I witnessed autumn colours at their peak in Kyoto at Tofukuji and Daigoji, which I can really recommend. Tofukuji is always packed with people (no tripods) but Daigoji was perfect for a peaceful stroll that day.
Anyway, attendance at fall colour spots tends to be less crowded and less hysterical than at cherry blossom spots! The fact that the seson lasts for a longer time and is more predictable in the former case probably helps.
Cheers,
Fabien