Don't put fish in right away. I'm sure they have had lots of die off using shortcuts once the cameras are off. I've heard mixed results about live sand and most say it's not worth the extra money. Use regular sand and seed it with a cup of sand from another tank (perhaps trade a cup with your LFS
). I would only use the instant cycle to help start a regular cycle, that's it.
Everyone always says "nothing good ever comes fast in a saltwater aquarium"