I stocked Coppernose Bluegill (2 to 3 inch) and Redear sunfish on May 1 last year. About 30 or 40 of the bluegill spawned in late September and early October. The fry didn't grow very much over the winter but there were lots of them. The bluegills are starting to build nests now and will be spawning soon. So they do spawn before two years old, at least the Coppernose do.
I also stocked 5 lbs. of fatheads on April 1 and 5 more lbs. on May 1 last year. The pond was full of fatheads by the middle of the summer. There had to be thousands of them. A friend of mine had put 12 big bass (14 to 22 inches) in the pond around the middle of April. The bass didn't seem to have a lot of effect on the numbers of fatheads in the pond. The bluegills and Redears stayed hidden until they were about 4 or 5 inches long. After they started swimming around the pond the fatheads began to disappear. By fall you rarely ever saw any fatheads.
I'm not an expert by any means, but in light of my experience, I think that if you stock the 6 inch bluegill and feed them then you wouldn�t have to stock fatheads at all. Then after the bluegill spawn, you can stock small Bass. The fatheads aren�t going to be around for very long anyway.
The usual recommendation for stocking ponds is to stock bluegill and fatheads the first spring and then stock bass the second spring or summer.
I am surprised that someone with more experience hasn�t answered your inquiry. Maybe the new format has slowed them down.
Larry