It depends on the weather. Do not prune before the end of October. You need it to be cold enough that there is no chance of beetles moving about. Snow on the ground is a good indication and your oak should be dormant. I am giving you a link to a publication that has in bold letters "Always check the oak risk status" If you click on it, it will tell you the status. https://extension.umn.edu/plant-diseases/oak-wilt-minnesota i