Welcome!
We're at 2 months out and still haven't heard from Chandlyn, some people are in contact with her way before that. It seems kinda random to be honest.
As for the travel date/wedding date, if you're legally getting married in Jamaica you need to be there 48 hours. The Riu seems to require 72 hours, probably so they can do the organization and stuff. If you have your heart set on getting married September 27th, I would plan on arriving September 24th. The hotel is a bit flexible with the 72 hours in some cases from what I've heard but don't count on it. Also, what if you have any travel delays and don't make it to Jamaica more than 48 hours before your wedding time? That'd be a major problem.
Hope that helps!