In some places you can start buying eggnog around September, but normally it’s sold in November/December
You can make eggnog in about half an hour
While culinary historians debate its exact lineage, most agree eggnog originated from the early medieval Britain “posset,” a hot, milky, ale-like drink. By the 13th century, monks were known to drink a posset with eggs and figs. Milk, eggs, and sherry were foods of the wealthy, so eggnog was often used in toasts to prosperity and good health.