31 days before your trip is the point at which points can be put back into your current UY without penalty. If you wait longer than that the points go into a holding account which means you cannot book more than 60 days from check in and you cannot bank or transfer those points. If you cancel on the day of check in you lose all the points for that reservation. You can change reservations ie from one resort to another at any time up to the check in date subject to availability of rooms. If you use less points and there are some to go back to your account it would follow the above rules. If you are inside the last four months of your Use year you will not be able to bank them however and they must be used by the end of that UY.