Most waiters and waitresses learn through brief on-the-job training, which usually lasts a few weeks. Apprentices usually work with an experienced waiter or waitress, who teaches them basic service techniques. The average growth rate for all occupations is 7 percent. It takes a year or less to become a waitress.
That's how long it takes to learn specific waitressing skills, but it doesn't account for time spent on formal education. They were supposed to train me for a month, but they only trained me for a week and then I was alone. The longest training period I've ever heard of was two weeks at most (for an extremely high-end position) and the sudden change in training duration is more than suspicious.