CONGRATS!
BUT........
I hope you are ready. Octo's are probably the best escape artists in the hobby and most keepers silicone glass tops right to the tank and have small locking openings for maintenance, feeding, ect.
Also ammonia, nitrate, and nitrates must be kept at ZERO. These inverts are VERY delicate.
Most agree that 1 year is considered long term for one of these animals.
I have seen a couple that were killed by being sucked into the filter/overflow so be prepared.
On the plus side they are truly amazing animals to observe and are rewarding animals to keep.
ENJOY...........pics please!