Unreserved Bus from Shirakawa-go to Takayama

I wonder how easy it is to get onto an unreserved bus from Shirakawa-go to Takayama on 29 December? We are a family of 4 (2 adults, and 2 children age 6 and 8 years old). How early should we queue for the bus? Are there many buses heading to Takayama from Shirakawa-go? I am trying to evaluate our chances as we do not want to get stuck in Shirakawa-go. Thanks

The timetable is there, with reserved buses marked with a red R letter

https://www.nouhibus.co.jp/route_bus/takayama-shirakawago-line-en/

Roughly one bus out of two or three is non reserved.