The regular pot that most people use for their CP's is a 6-inch pot. I would reccommend that you use a 6-inch pot, if you don't have a pot, you can use a plastic cup, or the insulated ones styrofoam cups that are 6-inch tall. The deeper the better!
To sprout gemmae put them on top of the peat, since gemmae is small, use a pencil or finger, tweezers and put them in the place you want them to sprout, you can just throw them in the peat. the peat must be really moist, and the gemmae should be getting artificial light, or regular light, but for only a few hours or minutes, and the most important part is giving them humidity and water, too much light migh cook the gemmae, so becareful with that.
also you can use a plastic, or wrapping paper on top and punch some holes in it, that is to keep the peat moist and humidity high, if doing this, becareful no to put them in direct sun, or they will cook within minutes, take it off when giving sun, or artificial light, and they should sprout in 2 days or even one depending on the variety. Start acclimating the seedlings very slowly to a lot of sun, and keep them moist, when you think they have aclimated correctly, start decreasing the water, and just leave them moist, if keeped wet, it is probably they will have root rot. It is like germinating seeds.
Good luck!