Lets’s start by listing the known dates and locations… (source)
- Fukui Cave, Japan (Jomon), calibrated at 13,900 BC to 12,300 BC.
- Gaysia site, Amur river, Russia, calibrated at 14,050 to 13,200 BC.
- Khummi site, Amur river, Russia, calibrated at 14,300 to 13,650 BC.
- Odai Yamamoto 1 site, Japan, calibrated at 14,900 to 14,250 BC.
- Ust-Karenga , nearer lake Baikal, calibrated at 11,800 to 10,500 BC.
This makes the oldest Jomon pottery now about 16,500 years old, Russian 16,000 years old
Given the distribution pattern of the pottery, i’d say it spread along the river pretty quickly. The Russian sites are in the Osipovka complex, and further west at the Ust-Karenga complex.