I'm in the process of trying as well, if I can start mine I will let you know. If you start your please let me know.
It may be a seasonal thing, starting in the Spring so we may have to wait. Norma

My previous attempts Norma were in potting soil and they just rotted. Perlite can do miracles with cuttings, or tubers in this case. Also, the Jicama was simply placed on the surface of the perlite-not even as much as pushed down hard!
I can't imagine it waiting until spring to sprout top growth..it probably thinks it's back in tropical Mexico and the rainy season has returned-lol.
I also kept it in the warmest room in the house.A room where i keep some large Aquariums and has a large window facing southwest. Gets hot in there. You might try a heating pad to increase the odds-good luck.

I have mine sitting on it's side in morning sun, waiting for the roots to start. I don't even have the base touching the soil at this time. This is sometning I haven't done before, so it will be a learning experience for me. Have you ever grown tooth picks? LOL Norma