They usually declare more into inventory than is actually sold at any given time. This provides some leeway to find accommodations for new members.
As more contracts are sold they can simply increase the available inventory, but if inventory is already rented with cash reservations, the member inventory can't be further expanded for that date.
As of this time, it's likely that member inventory is no higher than 20%- 40-50 rooms, depending on the configuration of studios/1BR/2BR.