BG can reproduce at 3"-4" in size. This will be especially true in a new pond where the BG are trying to fill the biomass such as yours. If you have no predators in your pond and your BG do spawn which is highly likely by end of summer, you are going to really need to work hard in removing large numbers of the small BG or yes, you will end up with very bad stunting.

In a small 1/4 acre pond, this can easy be done via seining, trapping and other means of manual removal. If you are trying to grow eating sized BG, you almost cannot remove enough BG. The few that are left will grow to eating size with the limited competition you create by removing the vast majority of the offspring.