MN Fisherman, Welcome to the forum. Being that your pond is such a new one, your oxygen demand this winter should not be a concern. I don't think you have too much biological activity to consume more oxygen than is present in the pond now.

My only concern is as Eric's that the ice may tend to get thick enough to not give your fish your walleye enough area.

As Eric said, if you make it through the winter I would suggest letting the food fish take hold before adding any more game fish. Good luck!