@MysteryChicken is working on them and has been for a long time. She can tell you how long to expect to be breeding. I would think at least 6 generations to be big, and JGs take over a year sometimes to be mature, so this is a truly long project.
It's possible, but again, it might take you 10 years or more to be close to the goal. You would have to hatch out a lot of chicks in each batch and be quite ruthless in who stays and who is culled from the flock (*note Cull does not mean Kill, just removed from the potential gene pool). Several recessive traits have to be locked in, and you'll want the silkie traits that are dominant to be homozygous, which means test breeding and more culling