Should i tell my online friend who's younger than me i have a crush on her?

This is basically my situation with her in a nutshell: I saw an answer from her on yahoo answers where she gave a lot of insight on writing. She added a link to her email, and I emailed her about a book series I'm writing. We ended up talking a lot on kik and a good friendship formed between us. This started in April 2016, at that time I was 17 and she was 14. Her birthday is in October, so she'll be 16 soon, and I'm thinking about telling her how I feel the day after her birthday (since I was recommended to not start anything until she was 16). It's hard to do our friendship justice with a brief description, but believe me she's had an incredibly great impact on my life and even though she's young she's very smart, (and I've seen pictures and videos of her on instagram so this isn't an imposter or anything) and I'd want her to know how mich she means to me.