It's easiest if you hem it right now, once the join is done, because you can baste the pleats together once it's hemmed, and the whole thing becomes a lot more manageable.

The depth of the hem is already set by the fact that you've done the pleats (i.e., once you've committed to pleating, there's only one place you can put the hem and still have the kilt the right length. And, you don't cut anything off the bottom before hemming - you just turn it up _once_ (i.e., you don't turn the edge over before hemming on the back side like you'd do with the hem of a skirt).

Barb