I just leave them on the plant until they have nice roots or the scape turns brown. A lot of times the scape will stay green on the side where the prolif is growing and the rest will be brown. I usually just plant next to the mama plant or pot it up and it grows great. Keep in mind that by the time I take the prolif from the plant it is usually the size of a full grown fan
Here's a photo of one I planted. I wouldn't have taken this one yet since the roots aren't very long but I broke the scape so I had to. As you can see it is a blooming size fan and has a scape and a bloom.
In this photo you can see how half of the scape is still green so it could have stayed put for a while longer if I wouldn't have broken it
