Usually within a week or so.
If the clown does not host within this time, chances are it never will.
Getting clowns to host with anemones is touch and go - you cannot force the relationship.
Clownfish are endangered,because people drop anchors on an anemone the same way we drop it on coral, Clownfish cannot survive without an anemone.
What are all the ways that a anemone protect the clownfish
clownfish
For protection, clownfish seek refuge amongst the tentacles of sea anemones. The tentacles contain harpoon-like stinging capsules called nematocysts that the anemones employ to capture prey and ward off predators. In a yet-to-be resolved biological mystery, clownfish have mucus on their skin that somehow protects them against the sting of their host anemone. As a result, the clownfish are able to stick near their host which is avoided by most other fish in the sea. 'The clownfish gets protection by hiding sting-free among the tentacles. If you remove the clownfish, large butterfly fishes will eat the anemone,' said John Randall, an ichthyologist at the University of Hawaii at Manoa. Butterfly fish are predators of the sea anemone. In certain areas of the tropics where clownfish, sea anemone, and butterfly fish exist, clownfish scare off butterflyfish from their host anemone. Research has shown that if the clownfish are removed from the anemone, butterfly fish will move in and devour the anemone. So, the protection of the anemone afforded by the clownfish is part of the mutual relationship. In addition to scaring off predators, some scientists speculate that clownfish waste may serve as a nutrient for the anemones… There are more than 1,000 species of sea anemones found throughout the world's oceans. Only ten of these species share their niche with clownfish, which thrive in the tropical waters of the Indian and Pacific oceans. Each individual host anemone is home to one group of clownfish, which contain a dominant breeding pair and up to four smaller, subordinate fish. There are 28 known species of clownfish, so more than one species of clownfish may take to any given species of anemone.
In the wild, clownfish live among sea anemone and usually like having one in captivity, too, but you can keep them without an anemone host. They usually live in anemones in reefs in the Indo or Indo-West Pacific.
It will protect it
It is mutualism because the anemone wards off the clown fish's predators due to their poisonous tentacles, but at the same time the clown fish wards off anemone-eating fish, also ensuring the anemone's survival.
Clownfish eat the leftovers from fish on the anemone and algae.
The Clownfish feeds on the small invertebrates in the anemone which might otherwise damage it. Also it's suggested that the faeces generated by the Clownfish acts as a fertilizer for the anemone.
In their anemone
Clownfish have a symbiotic relationship with anemone. The clownfish deliver nutrients to the anemone in the form of waste, and the anemone protects the clownfish from predators. Anemones, like other cnidarians, have stingers called nematocysts which are used for protection.
Wild ocellaris clownfish (Amphiprion ocellaris) eat algae, planktonic organisms that float by its host anemone, and debris that clutter in the anemone. They are omnivores.