Avalon was born in Los Angeles at 5 a.m. on Aug. 5, and weighed 8 lbs. 14 oz.
"Mother and baby are wonderful," says a source close to the couple. "The whole family is thrilled."
Sofer, 36, also has a daughter, Rosabel, from a previous marriage. She and Bookstaver, 31, whose credits include The O.C. and One Tree Hill, met in 2001 on the Sci-Fi Channel series The Chronicle. They married in May 2003 before 80 guests in an eclectic ceremony performed by the bride's father, Rabbi Martin Sofer, at a rented Malibu ranch, PEOPLE reported at the time.
It remains to be seen what lullabies they will play for Avalon.