Florida Club is unique as usage is not considered by MVCI to be an exchange. Rather, it is like being an owner at all 5 FC resorts and making a home resort reservation. The only difference is that the reservation window opens at 6 months prior to check-in (or 7 months if booking multiple weeks). To make your reservation, log in to your account and select "book my week". From the drop-down menu, choose the resort you wish to reserve. If you are within the 6 month window you'll be able to select from studio, 1BR, 2BR full villa, 2BR lock-off, whatever is available at the resort you are reserving. You'll need to use an exchange company to get the 2BR with a studio. You may increase your chances of getting the 2BR if you use a Beachplace or Ocean Pointe studio for your exchange.
FWIW, I haven't ever had a problem locking off at a later date. Keep in mind that you need to select the 2BR lockoff, NOT the full villa at the time of reservation to do that.