I’d lowball it at two-and-a-half weeks. Tortuga’s off Haiti’s northern coast, so there’s quite a bit of travel time in there. Isla de Muerta must be way the hell in the middle of nowhere for Interceptor to get there in time for Elizabeth not to get killed.
Now that I look at the map again, two-and-a-half weeks is like if the ships had warp engines. I’m bad at gauging speeds and distances, but this should be a summer-long escapade at least.