"At 9 to 11 months, when infants start to be able to understand a few words, they produce pointing gestures. The emergence of pointing is a good predictor of first-word onset, and gesture production is related to gains in language development between 9 and 13 months (Bates & al., 1979; Butcher & Goldin-Meadow, 2000; Caselli, 1990). As explained in Butterworth (2003), pointing not only serves to single out the object but also to build a connection between the object and the speech sound [or signed word, I should correct!]." Source: https://www.cairn.info/revue-francaise-de-linguistique-appliquee-2008-2-page-23.htm
First of all, pointing gesture (usually at 9 to 11 months) is universal, regardless of spoken language or signed language. Pointing gesture is an indicator of communicative/language development in either signed language or spoken language.
Juli (age 8;3) initially handpointed and then, with quick transition, began to fingerpoint toward certain locations in space where she wanted to go.
Juli was able to direct me or a caretaker where she wanted to go by handpointing toward a specific location, especially a work of art or a photograph on the wall. She handpointed and vocalized at the same time.
In addition to handpointing, Grandma Z described how she followed Juli's direction by observing the baby's body leaning toward a destination. So much freedom for Juli now that not only she could crawl, but also she could handpoint where she wanted to go!
Just in a few days from the emergence of hand-pointing, I noticed Juli began to form an index-finger pointing toward things in the space.
One night Juli rested on my shoulder at 3 o'clock in the morning. I tried to soothe her to sleep but I checked and she was still awake. She was gazing at the hanging storage in long silence.
Then in lightning sudden, Juli raised her arm straight and pointed at the hanging storage. It was something like "Look at that/this!" I laughed. It was a moment that I felt she was talking with me in a sense of two-way communication.
A sentence in the article about "baby sign language" on a website (expertise on parenting) reads: "Keep in mind that simple gestures such as waving bye-bye and blowing kisses are a form of sign language." This phonocentric statement is unsurprisingly reflecting a mainstream ignorance.
This statement is akin to saying that sighing, yelling, and raspberries are a form of speech language. Rather, say they are a form of vocal gesture. That is, waving bye-bye, blowing kisses, and pointing are a form of manual gesture. Sign language and speech languages are linguistic, apart from communicative gestures, because sign language and speech language process similarly in the linguistic regions of the left brain, while gestures process in a different part of the brain.
Off the point: using sign language is a parallel to using speech language in term of bilingualism, not "communicating before talking" since sign language is already the form of talking. Signed language spoken language acquisition are on the similar timeline of language development milestones.