Sure, you could add the pectic enzyme now. Just pull a bit of the mead out of the fermenter, stir in the pectic enzyme, and then gently add it back to the mead. (This will reduce any foaming).
As far as nutrients, it depends on where you are in the additions and what you've already added and what the schedule is.
Broken Leg Brewery
Giving beer a leg to stand on since 2006