Whatever you do, don't be swayed by products saying that they can "cycle the tank in ______________ weeks", etc. It is a bunch of hogwash. 3 months will go by so fast, and it will be a great time to start your octo tank.
Your little octopus will appreciate having such a convenient snack in the tank. They must be pretty tasty because my bimac hunted for them even after she had eaten every amphipod in the tank (and I had hundreds of them). I felt sorry for her and added some more.
And the small things in your tank can be fun to watch, too. I love putting in small flakes and watching the amphipods come out to find a flake and hurry back to their holes. Lots of activity!