I use another Timeshare for the Carribean. I plan 2 yrs ahead for the Carribean, but I am wanting a two bedroom in Grand Cayman, when we go. Very hard to get, but I get it. Use my 2 yr window. I am interested in your question also.
Getting something in the Caribbean during June shouldn't be difficult assuming one has realistic choices and can do without a 2 BR. A 2 BR is possible but not likely. The Reef resort and the Westin will be the most difficult and possibly impossible. Cancun will be the easiest.