"Reach" is a Jamaican term that is often interchangeable (in this context) with the word "trip".
"When is your next reach?" and "When is your next trip?" mean the same thing.
It is usually a "destination" reference - "When did you reach?" means "When did you get here?" Jamaicans will understand both.
It is kinda like the "plug in" and "plug out" terms used here. If you "plug it in", the obvious opposite of that is to "plug it out". North Americans "unplug" things, which really doesnt make much logical sense. Plug it out is the opposite of plug it in, but most Jamaicans understand "unplug" by their interactions with North Americans and their TV programs and movies.
None of the above "reach" or "plug it out" are Patois, but just the dialect/slang terms used by Jamaicans.
