I've been doing 1 feeding a day, and letting them fast on Sundays because they're religious(joke). Yesterday my brother forgot they were not supposed to be fed and he fed them, so I guess it's Mondays now.Tank looks good! Keep it up!
I would imagine the duckweed is helping in reducing the ammonia. Fast-growing plants are great for nutrient control but keep an eye on how much you are feeding the fish. For a fish-in cycle I suggest minimal feedings to keep the ammonia low.
Also, how do I feed the shrimp blanched carrots? I tried yesterday night, but only the guppies touched them, and that was only when they were falling. Should I keep a large chunk or do I rip it apart?