What enzyme were you planning on adding?
The only one that is usually used in Cider is Pectic enzyme -- to protect against pectin haze during pasteurizing..... It works fine late in fermentation....
Others like the ones sometimes used in Beer -- Amalyse, Galactosidase, cellulase, protease, etc... aren't really necessary -- apples don't usually have much of the muck in them that causes haze in beers..
I did try out Galactosidase (Beano) during a round of fermenting on apple pomace (Non-pressed, crushed apples.....)
I didn't like the results.... It was breaking down starches in the pomace during fermentation -- resulting in Pomace Gysers in my bucket.... 2.5 gallons of total pomace per bucket and it was literally bubbling up and out of the top of a 5-gallon bucket.....
On the other hand, it really did break it down quite a bit -- I ended up with about 2 quarts of dry, pressed pomace when I racked it to the secondary..... starting from 4 gallons of pomace.....
I didn't like the flavor of the cider, though.... It had no flavor.... very bland and totally bone dry.... The enzyme broke down *Everything*.....
Thanks