First thing, wait atleast 6 months before adding any
anemone. Second, the anemone will pick it's own spot that it likes, usually a crevice in the live rock that it will put its foot into. So in reality it may not like the spot you put it at, and will proceed to move about the tank to find a spot it likes. I would honestly suggest spending the time while waiting for your tank to age and stabilize for the anemone to do as much research on the different species and requirements for them as you can.
The clowns may or may not host the anemone, don't be surprised if they don't take to it immediately if at all. Also be sure to anemone proof your aquarium, things like putting sponge pre-filters onto the intakes of your powerheads so it doesn't get sucked into one and torn apart like my anemone did after 4 days in the tank causing a crash and killing all the livestock. (yes, i'm still a little bitter over my RBTA nuking my tank)
Leave the livestock in the tank during water changes.
Sorry if my post comes off as mean, it's really not meant to. Text makes it hard to "sound" nice.