I wouldn't worry too much. You only ordered 200 dubia which is not many. Especially if that # is comprised of mostly nymphs. Even 200 adult dubia won't run through food too fast. Dubia are one of the more nibbling species of roach when compared to other medium/large roaches.
For instance my discoid colony completely devours anything I put in there (and I mean ANYTHING). Meanwhile my dubia colony takes days for food to disappear (sometimes a full week). Yet I never worry because each time I rummage through the egg flats in the bin I see more and more babies each time.
I used to worry much the way you are, when I first used to open the lid and not see a single roach out eating or running amok. Especially after watching all the youtube vids of roaches scampering left and right, with the sound of them marching loudly, lol. However, I've come to decide maybe those roaches in those vids were just underfed which is why they may be going bonkers for food in those online vids. Mine only seem to bumrush the food bowl if I offer them "Flukers High Calcium Gutload." Otherwise, with fresh fruits|veggies and my home-made chow they just take their time eating it, taking days to finish it off.
Which is why my discoids have come to be my favorite feeder roaches. Those guys PUNISH any food item I put in their bin! I love my orange heads too but mainly because of how beautiful they are. But anyway, don't worry too much. As long as your dubia start producing nymphs and nibble here and there you'll be fine. Especially since your temps are right and you have kept them dark. I wouldn't worry much. Only start to worry if 2 months go by and you don't see any new babies.