Here's my thoughts...
Bluegill and redear growth is what you should expect. Bass growth is what you should expect, having stocked 100 per acre. Had you stocked fewer, average size would be larger. 4-6 ounce bass should be 8 inches long.
Bluegill are opportunistic feeders, eating anything they can...they're not too picky. Bass only eat live food...other smaller fish. There's more sunfish food than bass food.
Keep collecting data on your bass. If they aren't growing at a satisfactory pace by mid-summer, start removing some of the smallest ones. Release the larger ones. At the same time, focus your efforts on raising more bluegill. Proper feeding, and timely fertilization will help raise more bluegill.
Regarding your "harvest bluegill" question, don't take any, yet. Wait until the pond is in its third year. Then, if you choose, take up to 50 pounds of sunfish. But, NEVER take the largest sunfish. Take the next size down.

Teach a man to grow fish...
He can teach to catch fish...