No, you are not guaranteed rooms at your home resort or anywhere else.
However, you do get a booking advantage at your home resort. You can book 11 months in advance at your home resort, while everyone else has to wait until the 7 month window to book at your home resort.
So what many people do, including us, is to make a reservation at your home resort during the "booking advantage" window, preferably as close to 11 months in advance as possible. Usually you can get your own home resort by booking 11 months in advance, unless it's a very busy time of the year and you don't book right at the 11 month mark.