Do you know exactly what type of anemone? What type of Clowns? Sounds like it may be a condy, in which, the chances of clowns hosting in them are not favorable. It can happen, and can take months sometimes, but it is not a certainty.
There is no guarantee that any clown will use any anemone as a host. Clowns can live without them, and if they're tank bred clowns then there's every chance they haven't even seen an anemone before
Looks like an Ocellaris Clownfish and a Sebae anemone. I still say just give it more time.. after a month or so and it still hasn't happen then start to consider it may never.. but it's still way to early to say one way or another.
I've also heard it can take months, almost a year. And they are right, sometimes never, and the clown you have was probably tank raised, I know mine was.
clarkii are the only tank raised clowns that will go straight for an anemone or thats what i've always been told i got one and it hosted my condy and ditched it's old one right away