You're early right now - most Marriott owners won't deposit their weeks with II until 12 months before check in or less. I'm a single resort Marriott owner and I'm allowed to make my reservations at 12 months before check in and then deposit my week with II.
I think your chance for a studio/efficiency is VERY good. Those are always the last to get booked because most timeshare exchangers want the bigger units.