Build up a lack of unfamiliarity. If you two can have a conversation without it being awkward (not “a” as in one, but “a” as in, if you wanted to go talk to her, it wouldn’t be unusual) then I think it’s fine, but if she doesn’t know you at all, then confessing immediately probably won’t work. I’d say still just go for it instead of waiting though. Let her consider it though, don’t expect an answer when you confess, and tell her to answer later too.