So, I've very recently (as in today) started a dubia roach colony. When I bought the roaches online I specified that I wanted half females, half males but for some reason they only gave me like, 2 females, a bunch of males, and even more nymphs... I mean, they're fairly big, but it's not obvious if they're male or female yet.
I was wondering if I should buy more females for breeding purposes or wait for the nymphs to get older, because some of them could be females? Is there, like, a certain ratio of males to females you need to keep when starting a colony?
2 females is a small number to start with if the goal is breeding, but like you said, the nymphs will grow up into adults eventually if you're planning to not feed from your colony until it establishes.
If you're in a rush to get your colony going, i'd pick up some more females.