Congrats on getting them past free swimming along with figuring out how to handle the spawns and hatch the shrimp!
BBS is always (imo) the highest protein / best thing starting out.
Mine continue to get BBS until almost dime size but above pea size I start adding crushed flake. How I handle angelfish fry support is they get fed twice a day (AM,PM). Introducing the flake I pinch, thumb/forefinger, rub/crush it to powder then 3-5 minutes later follow up with the BBS.
I don't think starvation food shifts are wise.
I wish you would write a book on angelfish breeding........