I'm calling it as her first official word! She started saying it yesterday afternoon. We were at the doctor for her 9 month well check (yes, a month late), and she was standing on my lap looking out the window and she kept saying "hi! Hiiiiiii!" And I was all like, "did she just say "hi"? No, it's probably just baby talk and it just sounds like she's saying hi." And then the rest of the evening she was saying it. She even waved and said it a few times. Here's a video of her saying it last night. It's at the very beginning. Right as she pulled herself up on my legs
So today when I picked her up from Aunt Jen's, I asked her if she was saying it and she said yes. She said she said hi to her husband when he got home! So there we have it. Miss Cailin's first official word is Hi!