I see no problem with putting in fatheads now. I'm pretty sure you fatheads will reproduce and you will have even more in no time. The perch may put a dent in them, however, although in my perch only bluegill pond they don't seem to keep up with them if the perch are fed pellets. In fact it seems the perch prefer the pellets over the fatheads -- at least this time of year.

Are you sure 50 walleye is not to many for a pond that size? They are quite the predators and need a lot of forage.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.