Redear are something you should stock because they eat parasite carrying snails which can spread disease. If they will survive your winters I would get some larger ones in right away. RES only spawn once a year so they will not become a prime forage fish like bluegill although some will certainly be eaten by your bass. The bluegill really are the backbone of your food chain, the fatheads are probably just a snack for your bluegill and bass.
EDIT: I just saw that you have hybrid bluegill and not regular bluegill. I would add some regular bluegill right away as your bass will decimate the hybrid bluegill in short order. Regular bluegill spawn throughout the summer and their young are the primary forage for bass, the hybrids do not spawn as often which means less food for your bass.
Consider adding a feeder. It will help your bluegill grow which will in turn help your bass. Good feeders are not cheap but they really help your fish pack on pounds. The capacity of a 1-acre pond is 100lbs of predator fish, with a feeder that number increases significantly.
