Unless the clown has had ick previously you are leaving much to chance on it fighting the parasite at this point. Aquired immunity will only have some affect but in a closed system it is not what I would call reliable or well advised.
If the QT
is set up and ready I would transfer the clown and begin treatment as long as you are sure
it is C. irritans
. Also check for the possibility of Brooklynella hostillis
The inverts will be completely unaffected by the either parasite and can be added safely without concern to the display tank provided no treatments have been previously used.