I wouldn't cut it down yet. You can do it safely after it goes fully dormant. I'd wait until late November. Or, you could leave it up all winter. This will provide more protection for the crown of the plant. Then cut it down in early spring, when you see the first signs of shooting.

If I cut it down, will it come in more full?

Yes and no.

Ornamental grasses tend to enlarge every year, and particularly in their first 2-3 years. They'll do it if you cut them back, and they'll do it if you don't. If you don't cut them back, the old dead foliage and culms will look awful the following year, and may indeed cause the plant's death.

Thanks for the info. I will definitely cut it back come November. Thanks again!

Isn't Maiden grass the common name for Miscanthus sinensis cultivars? My Miscanthus 'Gracillimus' hasn't even bloomed yet, they are sending up flower heads now. Usually they have bloomed by now, but we had a very cool and rainy Spring/early Summer this year, so maybe that set them back from flowering (as it did for many other warm-season growers).

I cut mine down in the spring because I like the way they look over the winter, although they do get smushed by the snow sometimes, and some of the fronds usually break off and get a little messy by Spring.

terrene, I was just posting about the same problem with my gracillimus. Mine hasn't bloomed yet at all.
I cut mine back in spring. They do get smushed by the snow, but it doesn't seem to faze them at all.