T5Nitro,
Thank you for your post. In order to better assist with your inquiry, we need to know what other specimens are in this aquarium, as well as the size (in gallons) of the aquarium itself. Additionally, the current pH, Ammonia, and Nitrate levels in the aquarium would be a factor in considering when to add the anemone.
Mike S.
LiveAquaria
Drs. Foster and Smith