"We join our heroes (on the road/in a tavern/in a dungeon) well on their way to (city name/getting drunk/formulating a plan for escape)" or whatever, plus a little background flavor text.

Maybe a couple sentences before if you need to set the tone for the world. Post apocalyptic high magic seafaring island nation or whatever, and now (hook for main quest).

It's really not a big deal, just give them a taste and fill the the rest as you go. They're all going to go somewhere you didn't prep in fifteen minutes anyway.