I suspect one feeding a day (and consider one fast day but it is very hard to make yourself not feed) is right for this growth stage. Some people even feed every other day. We don't seem to have issues with them overeating but a fast day seems to keep their appetite more regulated. If you start seeing rejection of food, try both this and some live crabs (live crabs a couple of times a week are a good idea anyway). One thing we learned to watch for at feeding time was elimination of the last meal. Once we saw that, we knew they would eat.
I am glad you are having fun with the brittle

. You can feed them easily by hand as well. Once it knows you are feeding the octo on a schedule, it will be a minor (but enjoyable) nuisance so it is helpfull to feed the brittle first.