When should I tell my sister the baby's name?

My husband and I FINALLY agreed on a name, and it turns out before we even talked about it, we were both calling her it. The name is Annabeth (like the girl in the Percy Jackson books - not unrelated, I have read almost every book in that universe during this pregnancy). We told my parents, his parents, and our siblings....except one of my sisters.

I love my sister and we get along great usually, but she has always given me an really hard time about how "into" books/movies/TV shows I get. My whole life has been trying to hide the things I like from her so I won't get made fun of. Now that I'm an adult, she literally categorizes my life based on what I was into at the time, like "Remember that basketball game during your Glee phase..." or whatever.

She's my only sibling who has read the Percy Jackson books, and now since we're doing a "fandom" name, and I know it's probably dumb but I'm terrified of her making fun of it, but I'm also worried about her finding out everyone else knew weeks before her.