You are going to feed the Jack guppies? Why not just feed it feeders?
Personally, I'm a believer in underfeeding. I have 2 BIG Jacks and they only get to eat 3 maybe 4 times a week. I hardly ever have ammonia/nitrite/nitrate spikes in my water. And, water changes are a lot less work that most.
They will eat every single day if you let them, though.