Need advice on how to cut a tulle skirt [no pattern] Sewing Machines Parts and Sales in Los Angeles

Hi r/sewing! I had a dress custom made for my prom and ended up needing to get it altered more which cost quite a hefty penny since the fabric is lined, so I decided to hem the tulle myself. There’s three layers of tulle on the skirt as well as an inner lining. The length is fine in the front but there’s a train in the back I’d like to cut off. The inner lining is the right length. Should I have someone cut it while I’m wearing it layer by layer? Or pin each layer and then cut it? Or match each layer to the inner lining and cut it? I was thinking the easiest way would be to hang the dress then pin up whatever layer I’m not working on and cut a single layer at a time to the length of the lining. Any advice would be appreciated! I’m putting rhinestones on the skirt anyway so any imperfections would probably be hidden, and since the fabric is dark it would be hard to see anyway. Here’s a picture of the dress: http://imgur.com/Zbsh426