If you are stocking perch as fingerlings you are fine but if you are putting in adults or if you are stocking heavy I would wait till spring. Yellow perch in northern ponds are hard on fatheads. They totally wipe them out fast in ponds without lots of cover. I am in Wisconsin and primarily raise perch without feeding. There is absolutely no such thing as too big of a forage base and the winter will give the fatheads born this year time to grow and find hiding places. We see the the fatheads swimming under the ice so they do stay fairly active in the winter.