Well dubia turn into a hobby of their own if you've never kept them before. My pixie ate a dozen crickets and a single gravid female so they could really eat a few a night. You only want to feed out males for the most part.

I would not start using your colony until you have a few hundred adults in the colony. I normally wait 6 months before I start feeding from my colony. Having only 5 adults to start is going to take a very long time to have an established roach colony.

a good starter colony should have 50 to 100 adults and 2/3 being female.