It is not wise to just let them do their thing. Things can and do go wrong in breeding including the dog or bitch doing serious bodily harm to the other.
Have you done any health testing, especially the DNA Marker Test for Fanconi Syndrome? Do you know the puppy lemon laws in your state? Depending on state law if you produce a puppy with a preventable inherited disease the new owners can sue you for all medical expenses related to that disease.
Do you have $2000 in the bank to cover an emergency C-section? Though not the norm, they are sometimes necessary and most vets demand payment at the time of service so if you don't have that money available it could mean you lose the entire litter and your bitch.
Do you have homes already screened and waiting for the puppies? With the current economy there are less people in a good financial position to adopt a dog and to pay for the necessary care through its life. Are you prepared to take back the puppies you produce for their entire life? If not, do you understand the reality that if they end up in a shelter they will likely spend their last days confused, scared, and then euthanized in the arms of a stranger? Basenjis do not do well in shelters and if there is not a rescue to step in many do not reach adoption.