Watch the time-lapse video how the bilingual ASL-speaking kid of Deaf parents acquires the ASL sign BOY in early language development from baby to preschool age.
The "O" handshape is one of few unmarked handshapes in 50+ handshape prime chart in ASL. Because the handshape is unmarked thus natural, it's possible for the child to form the handshape without handshape error. An ASL-speaking baby may use the unmarked handshape "20" in their phonological process before forming the correct handshape. Each child develops at different pace.
In the video at 1:3, notice that the baby self-corrects the location of the ASL sign. At age 1;7, it looks like she's checking out a boy, asking mom (translated from ASL as) "Who is this boy over there?" Ha, kidding.
Note that "baby sign language" is harmful cultural appropriation. There are no such "baby signs" as much as you don't call English "baby English" nor "baby speech". Parentese, older known as motherese is commonly used in both spoken language and signed language throughout the world. Baby sign language is one of some manifestations of oppression of our Deaf people and our signed languages. Deaf children have been forbidden from signing their very own natural (signed) languages during the critical development of language in name of speech.