Some clowns are better at it than others, natural instinct and all. Wild caught clowns will instantly go in one. Tank raised don't know it yet, most have luck with them hosting in just about everything from Anenome's , Xenia, Euphyllia's, etc.
Yours might go in there in 2 days, 2 weeks, 2 months or never. You don't really know.
I do know a few tricks, that sometimes work in doing so.
1. I've used a laser pointer before, fish will chase it just like cats. I've herded them right into one before, then they never left.
2. Gotten one of those 'Lee's Critter Carrier's' from Petco, that's just large enough for the anemone and fish, put it in there, put fish in, sink it. ( with anemone on a rock, for easy removal) Once they touch it, they are usually in love and won't leave it, then move it back to the tank where I want the anemone.
3. This only worked once, and you have to be careful, but I only fed the anemone, with a turkey baster, so the food was in the vicinity of the anemone, one would touch it trying to snatch food. And then stay the other would naturally pair up with the other clown and hang out.
Hope that helps.