I wrapped my first cuttings Christmas Eve, with a second batch on New Years Day. All very good takes. I'm on the fifth batch now, having wrapped cuttings from a friend who potentially discovered a "lost" polyantha in her town.
After some discussions and questions on Garden Web about a few points, I decided I should add a few photos to illustrate.
No, you don't have to wait until there are actual roots to pot up the cuttings. Callus at this stage of development can work just fine.
Yes, you can wait until there are actual roots, but it seems the longer you permit them to sit in the dark, damp paper, the less likely they are to succeed. Until they are exposed to light so the green parts can photosynthesize their own food, they are operating on whatever levels of stored nutrients they contain. Permit them to use up their stores of food and they have nothing (or not enough) left to help carry them until they can push out roots to take up more resources.
Some find covering their cuttings with bottles, bags or placing them in a greenhouse or terrarium helps prevent them from drying out until they are rooted. If that works well in your conditions, great, but it hasn't worked for me here, at all. So, I plant them deeply in the cups, like this.
Most of the cutting is now encased in damp, cool, dark potting soil, much like when you mound or hill up a newly planted bare root. It works for both for the same reasons. Warmth and light stimulate growth buds to develop, resulting in new leaves and canes, often to the point of flowering, whether there are sufficient roots to support the plant or not.
Encasing the cutting or newly planted bare root in soil, only permitting the top few inches to be exposed to the heat, dry and light, keeps the cutting or plant cool, darker and damper which stimulates root growth instead of cane, leaf and flower. This has successfully permitted several hundred wrapped cuttings to continue rooting and developing for me this and last year.
As I see roots filling the bottom inch or so of soil, and top growth being produced, they finally reach the stage where I'm comfortable lifting them in their pots so more cane is exposed and more soil area provided for more root development. It's an easy shift to make.
I tilt the soil ball out of the cup, add enough soil to the cup to elevate the cutting so it will be situated in the cup at what should be the proper planting height, then set the bottom of the soil ball back in the cup. Gently pull the soil around the cane above the root area away from the cane as you push it into the cup to fill in around the roots and soil. You're really just trading spaces it occupied from above the roots along the cutting, to below the roots where it permits more root growth room.
Until now, that extra soil kept the cutting dark, cool and damp while it rooted. Now it can be exposed to the hotter, drier, brighter conditions without having to harden it off as would be required had the cutting been covered by plastic or bottles, or grown in a greenhouse or terrarium.