while you set your tank up and let it mature you will be getting a bit of practise at keeping a marine aquarium (another reason why we suggest 3 months ) and during this time you will gain experience and confidence with your tank.
Anything specifically about heaters you need to know? just ask
Don't forget to add a few mollies or other fish during the cycling process. Don't make the substrate too thick. The octo will constantly re-arrange the rockwork in your tank, if you do not want this to happen, youcan use superglue to glue them together.