Dave,
Congratulations to your son for expecting a baby girl.
I'd say that I am glad you were able to identify the condition this early. In my son's case, I was caught by surprise and completely unprepared. He was born with Pierre Robin Sequence, a condition which among other pathological issues encompasses a cleft palate.
My suggestion is that you locate your nearest Children's Hospital and come in contact with a Surgical Coordinator. They will immediately provide you with details about the cleft palate condition, schedule necessary appointments, coordinate meetings with the Neonatal Craniofacial Surgeon, and guide you through this procedure.
Now, there are different opinions about when the operation needs to take place. In the past, surgeons suggested to wait 3-6 and in some cases 8 months. My son was operated at the Children's Hospital of the Kings Daughters (CHKD) in Norfolk, VA by Dr. William P. Magee, co-founder of Operation Smile. Among many advocates, he supports the method of Early Intervention. Dr. Magee operated on my son on his fourth day of age. Expectantly, the results were quick and remarkable. The corrective surgery left nothing but a few faint memories.
Our story is available at:
http://www.cleft.org/families/theodoros.htm
I am certain that your granddaughter will be a bundle of joy.
Good luck and God bless
Gregory
(11yoB, PRS)