User blog comment:WillTurner101/In Your Opinion/@comment-1984959-20120426045122

An excerpt from On Stranger Tides: The Visual Guide:
 * Did you Know?
 * The quest for the Fountain of Youth began several years back after a pirate showdown with the East India Company. Barbossa stole Jack's ship, the Black Pearl, but Jack found his own small vessel and had already stolen Barbossa's map and set off toward the fountain.

So if one were to take that info seriously, several years could be at least 2 or 3 years...but no more than say 4-5 years. Personally, I'd go from maybe 2 or 3 years, as it seems a bit too weird for OST to take place more than that many years from AWE. This last bit is just my opinion of course.