This is where it gets interesting. The only publication showing dichotomy type I know of is the article by Bill Reid and Mark Coggeshall in the link 2 posts up as gtr_nc243_018.pdf. If you look at the second page in the document, only 4 varieties are protandrous. They are Football, Knuvean, McGinnis, and Victoria.
I have the following varieties that are not in the list:
Sauber #1, Lane
And these that are:
I suspect most of the varieties of walnut available are protogynous but since their leaf out dates are up to a month apart, there is pretty much continuous pollen available in my grove. Sparrow is an outlier. I have always thought Sparrow was protandrous, but Bill lists it as type II.
The short answer is that I don’t know of anything that shows pollination dates for walnut. This would be a very good question to ask Bill Reid or Mark Coggeshall.