From my personal experience, the leaves are between 0.5"-3.5". Because they're bulb plants, I'm constantly removing new plants and rehoming them to other areas of the tank. So as long as you don't have very small foreground plants (HC) I would put it in the foreground. You can trim them control their length: let them grow and they'll reach the surface, then cut the stems. The next growth will then be shorter. I will try to send you a photo soon so you can see the size difference within my tank.
Re: N. stellata. have one on its way in the mail. how wide across does the plant get at the bottom so i know how much space to give it? also how tall do the substrate leaves get so i know if i should put this in the foreground or midground? Thanks.