The biggest hurdle will be to get (and keep) them eating. Expect to lose most of them (even in nature, few make it past the hatchling stage). Feel free to try any small foods EXCEPT brine shrimp. We have found that both octo and cuttle hatchlings appear to eat the brine shrimp but fail to survive due to the inadequate nutrition (this includes enriched brine). Shore shrimp make good second foods but initial foods are difficult to define (I used frozen Cyclop-eze for the mercs and briareus but it is no longer available). I think I would try various frozen several times a day in addition to live mysid shrimp. If you separate the hatchlings into smaller containers, use the water from the main tank for initialization and water changes (vs not newly created water) as it appears that massive deaths occur after a water change.
It has been a l o n g time since I have attempted hatchlings but here is my journal for my attempt (2 successful to adult) with
O. briareus. If you scan the Cephalopod journals until you see a prefix of Octopus Eggs and then click on the green prefix, a list of other egg hatching attempts will be displayed. Unfortunately, the prefixes are incomplete so you might also try searching for hatchlings or babies for other journaled methods.