Every overnight is different, @peter. Everything varies: from amount of time spent, to number of fun times, to activities. Talk to your escort to set everything up. Remember, communication, communication, communication is the key.
In my case, a typical overnight usually ran from 7pm to 7-8 am. Introductory light or heavy fun, dinner, heavy fun, sleep, maybe some middle-of-the-night fun, definitely morning fun, optional breakfast, and goodbye kisses. But it varies, I cannot stress it enough. Good luck.