When did your baby start babbling?

My daughter turned eight months old today and makes sounds -- cooing type noises and squeals when she's happy, mostly. She also has this "ayayayaya" noise that she does a lot; she loves to see how loud she can get with that one, lol. However, she hasn't really done anything that seems in line with babbling -- "babababa," "gagaga," etc.

I'm hoping I can get some reassuring answers on here, because the mom groups I've asked this question in were just irritating. Like, no, Susan, I do NOT believe that your six-week-old is babbling, lol.