Did you harden the albumen? Methods of hardening include aging, steaming, heating, and an alcohol bath. I usually make albumenized paper in large batches so that it ages, but I also steam it anyway to humidify the paper so that it is supple for sensitizing.
I float the paper on the nitrate solution and let it drip dry, and it curls as it drips. Silver nitrate stains everything, so put a dropcloth or several layers of newspaper or something under the paper as it dries. Also, be sure to wear gloves, eye protection, and an apron when working with silver nitrate. I weight the corners so the paper surface isn't damaged as it dries.
Normally I do this the night before printing. I consider the paper to be good for a day after sensitizing. I've tested sensitized paper that is months old, and it's actually usable, but it loses about two stops in speed, so it's not practical. It browns slightly as it ages, but that bleaches out in the toner and fixer.