...technically cycling can be done without live fish, it just can't be done without an ammonia source. Pure ammonia, fish food, and frozen shrimp are other common methods.
When ammonia is present, bacteria convert it into nitrites. Then a second bacteria colony forms and converts nitrites into nitrates. If your ammonia is being processed, nitrites should be present. How long has it been cycling? Maybe they're just too low to register yet?
Definitely right about the time though, this is not a quick process.