My instinct would be to feed as much as they'll take as often as they'll take it. Just keep an eye out to make sure they're eating it. You can probably run a wifi camera off the battery on your fish feeder if the charger is big enough, and they're cheap.

In my (established pond with regular BG), I was never able to get them to take to a mid day feeding. So in the spring and fall I'll feed at dawn & dusk and in the summer and winter just at dusk.

grower of champion bullheads