That is what I did, I fed rotifers up to about day 10, but introduced bbs on day 5. I ordered OTO on day 5 (lack of planning there) but Reed is in California and I'm in Florida so it took me 5 days to get it. So I started OTO a little late, on day 10, but they all took right to it. I'm at day 20 and B1 is still plenty big for them. I'm guessing i'll be able to feed it for at least another few weeks.
Now I mix between crushed flake, OTO B1 and Cyclop-Eeze.